The AC Tier 2 Support team looked into this and suggested looking at apps/extensions that may be conflicting with the "drawing" (i.e. showing on screen versus actually being in the BIM database).
We did try disabling/removing some Windows Apps from startup (not Archicad extensions) on my computer, they included TinyTake, Skype, among others.
Also, a trial period of CI Tools (for Archicad) expired, disabling those extensions on AC.
I am not sure exactly what did the trick, but we are back to smooth operation. Let's consider the issue closed until further notice.
**Note** whatever we did helped BOTH the AC23 Dimension problem and an Adobe InDesign problem with keyboard shortcuts (i.e. the "CTRL-D" command not working).
AC 23 | INTEL i9-9900 64GB RAM| NVIDIA QUADRO P1000 4 GB GDDR5 |WIN 10
USER SINCE AC 19