Fonts, font caches, and corruption can be wicked hard to find.
Do you manage fonts, or is it just a system font?
Duplicate the database, open the duplicate, change font on report page to another system font.
Close the database, open the database, change font back on report page.
Maybe recover the copy database, note any errors and test the recovered database.
Open the database on another computer, and or with another user and test.