Period mappings not working properly for data integration

I'll admit; the title of the question isn't totally accurate as I know for a fact it's something I'm doing wrong, but for the life of me I can't figure out how to fix it.

I'm trying to run an integration to move data from Planning to the GL in ERP. When I was first brought on to this position, the integration seemed to work fine, but over the past year, I've been having difficulties getting it to function correctly. The problem is that when it creates the output file, the integration isn't appending the year for the period mapping (i.e. instead of "Jul-25", for instance, it's just putting "Jul"). This of course is causing it to not function.