Rename sometimes fail

Hi,
I use tMM on Windows 10. When I start tMM by commandline and the option -update -scrapeUnscraped -rename -checkFiles tMM do almost the job fine. When the mediafile is used by another process, tMM does not rename this file (that´s OK). But when the mediafile isn´t used by another process anymore, then I had expected, that tMM renames the file. Unfortunalety tMM doesn´t. Is there an (undocumented) option to check alle files?

Second question: what is the difference between the options “-rename” and “-renameNew” (by the way: I tried both variants).

Thank you for your help
Johannes