Workaround for KB87371: Unable to save a process or file path in the On-Access Scan policy
just came across that problem and after searching what the problem may is, I found that KB entry. (We had done a fresh 5.3.2 install and migrate/transfer agents from the old ePO – so I first though maybe it was my fault)
As I had to add some changes quickly and cannot wait for the hotfix, I did the following workaround:
Export Policies (VSE e.g.).
Open that saved xml file and look for the right section –e .g. (or just look for some known process entry)