I ran another 78X flight last night Singapore to Manilla (3 hour flight) and indeed the problem showed up again. Not at first though. It slowly appeared as the flight progressed but not as extreme as my previous pics which was a 6 hour flight.
At a guess, it’s related to the heat blur. And it could possibly be “time” related. Longer the flight, the worse it gets. Ill try a longer flight tonight with a different skin.
I’ve never noticed any lines but I never use the default 748 skin. If you check the cargo variant skins, you’ll see they’re all fine.
EDIT: 2:30 hours in with the Etihad livery and it also appears. It seems this is a problem with the aircraft itself. I’ve logged a bug report. Apologies to 4Simmers and the livery artists for my incorrect assessment on the Singapore livery.
My frustration about the 748i liveries and the lack of support response, still stand though.
EDIT: No issues with the default Boeing skin after 3:30hrs of flight. So it may be the 4Simmers texture pack after all. We know of Singapore and Ethihad having the problem, so it’ll take a while to test all the other skins. I’ll keep everyone updated.
EDIT: This is proving to be a very time-consuming test of narrowing down this bug for a 3rd-party developer that still hasn’t even bothered to reach out to me either officially or through here. I’ve performed the test with 6 of the liveries so far under the same conditions and only the Singapore and Etihad ones appear to have this issue. I’ll continue to post any relevant updates.