Dust removal "busy" dialog sticks when quckly adding dust spots

Lightroom Classic 15.5.1 and prior versions. Using MacOS, but I doubt that matters for this bug.

When using the Dust removal tool (in the Distraction Removal panel), if you rapidly add dust removal spots, the “Removing New Dust Spot...” dialog will stick and not disappear even after LR has finished adding the spot.

Steps to reproduce:

1. Enable Dust removal.
2. Start rapidly clicking multiple spots, without giving each time to complete.
3. The busy dialog will popup, timeout, but fail to dismiss automatically.
4. Manually press Cancel to dismiss it yourself.