Could you send me a link to a file you’re having a problem with?
Was this problem ever solved? I'm having the same issue.
There was no follow-up, but I personally found a bug the other day in this exact script.
When you encountered this issue were you attempting to add inbetween frames to a file with group layers?
Yeah, I have two groups among my layers.
Okay, currently the script doesn’t handle layers in groups. It will result in the observed behaviour where frames are only copied.
I’m working on a fix for that.
