It shouldn't be because of save game issues. But do try to reproduce it in a new save as well. Besides that, do you have any mods active? Mods are likely not compatible with any 2.4 version until they are updated.
Otherwise a good first step is to verify your files through Steam to make sure no files got corrupted when being downloaded.
Otherwise a good first step is to verify your files through Steam to make sure no files got corrupted when being downloaded.