Your description of the problems suggests you are a new user to LR. Please correct me if I am wrong.

Open LR in the Library, in the left panel choose Catalog > All Photographs

Select one of the Photos (make the border white)
Change the module to Develop

Is the image showing in the Develop Module?

The RGB values did not alter at all at the centre of the image, but there is some kind of image shift. This could be due to a tiny magnification change when the filter was either fitted or removed, by a touch on the zoom.

When I checked the green leaves, there is a very tiny change in the RGB values.

The highlights have the most significant change, but mainly in brightness values.

I restate my position: based on the original two posts, from a practical point of view there is hardly any difference between with and without a filter.

Yes, I can see differences, but that is by enlarging to 300% or greater and using the sophisticated tools in Photoshop to show those differences.

Tsliva has given the answer I would have suggested. though I would also suggest that in LR > Edit > Preferences > External Editing tab, the first block should be "Edit in Photoshop CC . . ." ensure colour space is Adobe Prophoto RGB.

LR Develop Module operates in ProPhoto, so the Edit in should also be ProPhoto as should Photoshop.

This reduces all the converting of Colour spaces to one, that is at Export, for printing and web, sRGB is the one to choose.

Try signing out, reboot, sign in again. sometimes works.

Don't update unless you have been shopping for new cameras. The update contains very minor improvements and a huge decline in import flexibility. That is apart from all the crashes it has caused (mainly Macs).

Choose the Brush
Check flow etc.
Check mask on and paint
UNCHECK THE MASK
Move the sliders
Done

It would play havoc with Depth of Field calculations

I say bring it on - and there is the Atlantic Ocean between us.

You right though, the notorious question is "Would you put a cheap piece of glass on an expensive lens?" Those people asking just have not thought it through:

A 12 element telephoto lens may cost $1200 and consists of:

12 lenses mounted into precision engineered mounts
A body with a camera mount and filter threads
A focus motor
A stabilising motor
An electronic or mechanical Aperture
Exterior controls and cosmetic designs

Deduct the cost of all except for one piece of glass and its local mounting and you are left with (roughly) the same cost as a good filter in its mount.

I look forward to it.

If you printed one of each at say 16x20" and the looked carefully, you will see a difference at the left and right sides. What I actually see when the image is stacked, is a lateral movement as though the image is wrapped around a cylinder.

Frankly, unless you were photographing a grid of fine lines, the distortion is not really noticeable. My wide angle lens (not a fisheye) has far more edge distortion than either of your photos depict.

I was looking at Oldtigger's comparisons, and the only obvious area that "shines" out is a bright spot in the second image which is located a short distance under the letter "d" This is darker in the "first". Again you would need a copy of each to spot the difference. I'm not using a high fidelity monitor, so spotting the sharpness difference I found "for me" impossible.

I don't own a clear or UV filter for every lens, but always use one in a dusty, salty or sandy environment.

I have never damaged a lens, but I have ruined a filter by enthusiastic cleaning with a lens pen!

The tests on your images I carried out with every intention of being able to say "a UV filter will degrade your image", but in all honesty, I can't say that.

EBTR is something I do a lot of the time, but I have no experience of UniWB. No disputing the outcome, excellent; did you shoot a "normal" exposed image by any chance?

I use a matt black card about 24" x 36" behind the plants, this usually changes to a dark grey which is easy to select and change to solid black in PP.

The result is the flowers and foliage colours are as shot and there are no shadows even with a single diffused flash.

Have to take care that shadows are not cast from flowers in front to flowers behind.

1 Shoot small jpegs
2 Make sure you are using the fastest card applicable to the camera

I could not see a difference until:

I loaded both images into Photoshop and aligned them into a stack.

Toggle the visibility of the top layer on and off

The centre of the image stayed constant, but the left and right of the image showed considerable differences as in distortion between each other.

I still have no idea which one was shot with the filter, but the difference between the two is very easily seen.

Using the Difference Blending mode to check the alignment, most of the flowers from the centre out were aligned, but again left and right shows non alignment or colour differences.

Both images look good in their own right so my conclusion is that it really does not matter - the difference is not very significant on the screen. If making large prints, the distortion might show.

The LR colour space is Adobe Pro-photo. Adjust the colour space in Photoshop to match.

Three years ago I was producing calendars. They comprised 6 double sided calendar leaves, a single sided top cover and a plain thin card back cover. The gathering (collating) was accomplished on the press, they were wire bound with a hanging hook, shrink wrapped and packed in 25's for retail sales.

I was using a HP Indigo digital press for the printing

1000 calendars = 6500 (print 2 up) impressions at 65 imp. per minute

The paper used was ordinary coated paper (Indigos do not need ink jet paper) which of course helped keep the cost down.

Seven years ago when I started this, it was profit all the way, four years later, the prices customers were prepared to pay did not cover the costs.

An Indigo press is one of the more economical digital presses, (I was using an entry level machine), capital and running costs in the first year was over $200,000 - and that does not include paying the operator.

You can't use a home or office ink jet printer to produce such volumes and expect to make a profit unless you can sell each calendar at a very high price.