Hi @zirekx
I hope you’re well today!
I admit I’m not quite sure if I correctly understand the issue. I checked on my own setup and switching checkbox fields between optional and required didn’t seem to change anything regarding formula editor/calculation itself.
I’m not sure which error messages you mean, also.
Can you explain the form configuration and behavior a bit more, please?
It would also be helpful if we could take a look at the form itself. You can export form from Forminator on your site and share export code or file with us via either pastebin.com service or your Google Drive/Dropbox or similar (just post direct link to download in response).
We could then import form to test site and check how it behaves and what’s happening so, hopefully, it would help solve these issues.
Best regards,
Adam