MXF Files 'In Use' Despite being removed from the Project

Hello,

I'm working with a Sony FX6 with files in MXF format. My typical workflow when logging my footage is to name them in Premiere, remove the files that are junked, and delete the junk files from my HD. However, when doing this, depsite the files being deleted/removed from the Premiere project, when I go to delete them off my HD is says the file is 'In Use' in Premiere Pro. This has never happened before in 15+ yrs on PP. With my FX3 and FX30 it's no issue, it only seems to have a problem with the MXF files off of the FX6. I'm using Windows. Any thoughts?