Display problems in the Editor window

Question

Hello everybody! 
 I am experiencing a problem with displaying a PPT file that looked perfect last Friday when I imported it into the project I am handling, which includes several file formats.. 
 Please see below to have an idea of what I am seeing. 
 I have also found out that this issue extends to already translated Word files included in the project (most of the segments look the same as below), while it does not affect .idml files, which display correctly. Is there any parameter I should (re)set? 
 Many thanks in advance for your help!

Jerzy Czopik · Accepted Answer

Go to File -> Options -> Editor -> Formatting display style and chose "Show all tags but do not show formatting". 
 The problem you have is caused by a font missing in your system.

Trados Studio > 1. Trados Studio

Display problems in the Editor window