Weird texture bug - one side blue

[Rubble_Maker]

Hi

I encountered a very strange texture bug, it appears on different addons (like the BAS Kiowas) and the addon I'm working on now; the right side of the vehicle looks totally okay (nice high-res texture, about 1024x512 in size) but the left side turns all blue.

I had this bug before and I somehow fixed it, but unfortunately I forgot how

So any idea how to remedy the situation?

Thx in advance