I installed Publisher 188.8.131.523 on Sunday for the first time. I created a document and wanted to enter some dummy text in two text frames.
Here is what I did and what happened (and keeps happening):
Create 1st text frame and enter text
Create 2nd text frame
Connect the frames (using the little triangle of the 1st frame)
Click into 1st text frame and select all of the text (Ctrl-A or manually)
Ctrl-C (You can also skip this step, Publisher will crash as well.)
Press "End" key
It doesn't make a difference whether I follow the steps above or whether I click the triangle of frame 1 first and create frame 2 afterwards.
Publisher is installed on Windows 10 Home 20H2 (Build 19042.630).