Using some tools multiple times in Firefox causes them to no

Using some tools multiple times in Firefox causes them to no

A bit tricky to describe, but here goes:

REPRO:
Work in Zoho Writer as you normally would.
Keep clicking on things like "Insert Web Link", "Insert Table", and "Insert/Modify Image".
Also right-click text selections and particularly pictures in the body of the text and "Make Link".

OBSERVED:
Eventually, pretty quickly for me (i.e. trying to right-click and add links to several embedded images), these tools fail. In other words, when I go to select the item, nothing happens. I see a quick flash of *something* on the screen, but that's it. Nothing else.
The only way I've found so far to get usage of them back is to restart my browser, which is really inconvenient. :(

EXPECTED:
Tools should continue working. :)