use of an ampersand & in a steam mission description when displayed in game, shows text up-to the ampersand, but then displays a questionmark ? and the rest of the text is missing. The missing text can be found in the RPT file as "Unknown entity: '[remaining description]' ".

to make this more interesting, the use of a semi-colon after the ampersand, results in just the text between those missing from the game and appearing instead in the RPT.