Glossary: Acronym appears totally arbitrarily

for my thesis I made a glossary with the glossaries package. Everything worked fine, but in the pdf afterwards I encountered a very strange behaviour. At the end of one chapter, randomly an acronym (PS) shows up. It’s not defined there in the tex file (but in the chapter afterwards).

I wonder why the glossary finds an entry on that page for that acronym. In the .glo file I can see that it finds this entry on that page, but is it not defined there, so no gls{PS} is written in the tex file. Deleting the line

glossaryentry{PS?glossentry{PS}|setentrycounter[]{page}glsnumberformat}{10}

from the .glo file did not help (I think it gets created for every compilation).

Does anyone knows how to fix it?