Thanks a lot for that example, I wouldn't have suspected it at all but
for some reason the actual sprite in that scene wouldn't work with erase,
however copying it and pasting a clone allowed it to work....might be
something to do how it was created in an earlier version, somehow?
I created a new scene and made a test like your own and it worked perfectly,
before going back to that tree file and discovering that issue.
Anyway, thanks to your help I've got what I wanted working in my project,
so thank you very much for your time and help :)!