That is odd. Looks like a system font may be missing.
Thanks Bob. I never found out what was the actual reason for the issue I described, but everything was resolved after I reset (trashed) my InDesign preferences in order to solve another problem.
The following operation worked for me (of course, I had to set my custom preferences again):
(Windows) Start InDesign, and then press Shift+Ctrl+Alt. Click Yes when asked if you want to delete preference files.
(Mac OS) While pressing Shift+Option+Command+Control, start InDesign. Click Yes when asked if you want to delete preference files.