I have a workflow that splits a PDF by pages, and then it saves to a specific location, but it's overwriting itself. I start with a 2-page PDF, split it into two single-page files but instead of gettting two files in the destination folder, I get one single page PDF.
I've tried this with splitting pages by segments as well and the result is the same.
Try using "Append Rule Name to Job Name" in Split.
Alternatively you can use the variable for the job number in the job group $FFwfDoc.documentSequenceNumber$ in Save. For instance: