Came across an issue that may be worth noting.
I frequently use the area measurement tool to outline a large building (picture the floor of a large apartment building, each with its own balcony sticking out). There are dozens of direction changes before I complete the outline. Shortly (coincidentally) after upgrading to Revu 21 a problem started where I'd be half way through the area and it would "self complete" as if I'd hit the enter key, requiring me to start over. After many instances of this I opened a case with Bluebeam software with many notes and logs going back and forth to no avail. Support finally suggested I try a new mouse.
I had been using a dongle-connected mouse with the dongle on a laptop docking station sitting on a battery backup (potentially interrupting the signal when the mouse is moved to just the right spot on the pad hanging from the keyboard tray beneath my desk). Because the dongle also connected my keyboard, I switched to a Bluetooth mouse so I didn't have to change out the keyboard as well. Several weeks went by. The problem did not occur. Out of curiosity I switched back to the dongle mouse. Within a few days the problem was back Kind of proves something. I suppose I could rearrange my desk for more proof but….
I had done a few searches on this and other forums and found nothing related. Hopefully this post will be of use just in case someone else runs into this.
Kudos to the support team for finding it.