Adobe Acrobat Reader stopped recognizing German characters

Hey everyone,

I'm doing some translation work that involves copying and pasting chunks of text out of scanned PDF documents (originals are in German). A few weeks ago, I noticed that Acrobat stopped recognizing German characters (specifically ä, ö, & ß) and now leaves an empty space where the letters are when copied and pasted into a text editing software (so a word like "hätte" reads like "h tte"). I just re-installed the program but still no luck. Any suggestions?

Thank you!