This is very similar to this: https://bugs.launchpad.net/ubuntu/+source/thunar/+bug/1679488
I have a similar problem: Open thunar on a directory. Modify one or two files on directory, come back to thunar and is totally non-responsive. CPU usage is 0 so probably is a deadlock. I test the patch from launchpad.net ( https://launchpadlibrarian.net/321070348/02_fix-deadlock-in-mutex-causing-thunar-to-hang.patch) and it solves my issue. My debian release is stretch and thunar version is 1.6.11-1. I hope it helps.
