I believe I have discovered a bug with the editor. If you click on a plaque, and then "edit events" to get to the plaque event pop-up, using the red "delete" button to delete events attached to the plaque makes it impossible to add any further events to the plaque. I've been able to replicate this consistently using the following process:
1. Create a plaque
2. Click on the plaque and "Edit Events"
3. Add a an event and save.
4. Go back into the plaque and "Edit Events"
5. Click "Delete"
6. Go back into the plaque and "Edit Events"
7. Try adding and event and save - no longer works
When I try adding an event now, I get the blue "Saving" pop-up, but the Event editor does not close automatically and when you exit the event editor and return to it, none of the events that I tried to add are there. I've found that everything continues to work fine when the "Remove" link to the right of every row is used to remove events individually. Using the remove link, I can add and remove events as much as I want, but as soon as I use the red "Delete" button the plaque becomes unusable and I can no longer add events.
I am using Chrome with the editor.