I am having this problem for a long while now. I can’t add libraries to a design file.
This works on older design files but not on the current.
Currently, I am using a workaround - adding what I need to an old design file and copying it over to the new one. This sucks though.
When clicking on “add to file” in the picture. It won't do it and this error shows up:
If you are looking into my account. A working example is the “landscape” design file.
And one where it doesn’t work is “SnapIT”
Thanks!