If you look at my post (https://forums.unrealengine.com/unreal-engine/marketplace/47568-chameleon-post-process?p=1485087#post1485087) you should be able to fix this by adding T_White to the two main structs in the Chameleon/Structures folder. All working fine for me now (I upgraded from 4.17.2 to 4.19).