You have a great lens but this is a effect it sometimes gives when shooting into the sun. I would either use the Steve Perry's take two shots with one shot blocking out the sun and use it in post if you must to remove flare but I like some flare in shots. I put the sun to the corner of the picture so the flare flows bottom in the corner and not in the middle of the shot. For me, I don't care to see the sun in the middle of the picture either. Try it again with the sun to the side and maybe not quite as wide a shot. I've taken inlet pictures of marsh lands with the sun in the corner and the flare is beautiful. Tastefully place the flare where you like it.

Spent last weekend in Charleston, SC area and one morning at Botany Bay Plantation Heritage Preserve and Wildlife Management Area on Edisto Island. Wanted to try some longer exposures of waves and surf. It's more complicated with having to check tide charts, wave heights, sunrise times and open hunting on the preserve. All the shots were taken with a Canon 5D4 with the 14-105 f4 kit lens at ISO 100. Shutter times varied from two seconds to 20 seconds and spent two hours on the beach going through the various shades of orange, yellow and red during the sunrise.