Hangs forever analyzing files

I had great hopes of Advanced Renamer but my first experience wasn't good. I selected all the files in my Pictures folder (3990 of them) and it starts analyzing files but at some 75% completed (according to the progress bar) the program stops responding and hangs forever. Using Microsoft Internals tools I saw that it's apparently done with all the files, no new file activity from that point, and it's just burning CPU cycles like crazy. Left it for two hours but nothing else happened. Is there a limit on the amount of files it can handle, or anything else I need to be aware of ? My version is 3.85, just downloaded from advancedrenamer.com. Using Windows 10, version 1803 (OS Build 17134.950). Any ideas ?
TIA,
Chris