Problem with Ipe GUI

I have encountered a problem with recent versions of Ipe (e.g., 
current version 7.2.12) so that fonts are displaced on screen on the 
GUI. See the following for an example of

http://renyi.ece.iastate.edu/hold/bad.jpg

If the .tex is recompiled (Ctrl+L), then some other characters may be 
displaced (there is no apparent pattern).

The actual correct display can be seen in the PDF version, as follows:

http://renyi.ece.iastate.edu/hold/good.jpg

This is only a problem with the GUI (on Linux with 
libfreetype.so=6-64, poppler 0.80.0, qt5-base 5.13.1). The problem 
does not show up with the saved / rendered PDF files.

Any feedback on how to fix the problem will be appreciated.

Thanks,
Zhengdao