It's not supposed to work with the IFV ATGM. It's not supposed to happen at all. There aren't supposed to be missiles that ignore flares. Painting allows missiles to lock targets they can't normally lock, and increase lock on speed and damage. If painted jets couldn't flare missiles, they would be completely useless. The second you tried to do anything other than hide behind mountains, you would be painted and killed. In fact that's already what's happening with the IFV there's literally no counter to it. If someone has an IFV and a painter, they can paint your jet from spawn on some maps and get a guaranteed kill