Unable to delete photos from some bursts

Photos refuses to let me delete photos from five bursts in my iCloud Photo Library. I can click on "Make a Selection..." at the top left and check off the photos that I wish to keep, but when I click "Done" I'm taken back to the library/album and nothing happens. The burst is still intact.

This is only happening with five bursts. Using this same method I was able to ungroup hundreds of other bursts in my library, but these last five are driving me crazy. User planetm seems to describe the same issue in this thread, but it was never resolved.

Any thoughts on what's going on and how to resolve this issue?