A bit more testing: I can delete one per time but the last one isn't deleted at all.

Thank you for bringing this issue to our attention! I can confirm this should be further reviewed and I have logged an internal bug report for our development team to investigate and address as necessary, in a future maintenance release.

 

This issue was resolved in the recently released 4.7.13 release. Please update in order to fix this issue, and if you see any problem after that point, please let us know.