I have an issue where a cube has been deleted, and I now can’t change the UX view to point to a new cube. I just get a spinning wheel in the view administration page. I assume this is a bug and I just have to delete the view / dashboard and start it again.
Yes if you can’t change the source if the original source is deleted then that sounds like a bug.
There is a workaround though: In Architect if you go into }ElementAttributes_}APQ C3 Canvas View and change the CubeName attribute directly for the view/sub-view/widget.