Comment actor prevents saving

[Room21]

Hello together – first forum entry here.
I'm currently using licenced Isadora 2.6 on a MacBook Pro running macOS High Sierra, 10.13.6.

As soon as I insert a Comment actor into the Scene Editor, I am not able to save either as regular save, backup, auto-save, run only or under another file name. If I remove the comment actor, saving is possible again.
Does anybody observe the same? Any ideas?

Thanks,
Room21.