Had this today, painters dropped some when putting the paint away then left it covered with an off cut. I think they tried to clean it up as area around the mark was stained and blurred as well.
it would not shift!
Applied solv all, blotted, worked away with citrus gel and rinsed and it weakened a lot but full colour would not go.
Guessing the type of paint was giving me problems as standard interior emulsion etc had no problems with.
Any ideas? Wrong product applied?