I am currently running the newest version of Anki (V2.1.33) on Windows 10, and every time I try and export a deck it brings up the folder to save it but immediately freezes and then crashes a minute or two later. I have tried removing any add ons but that does not seem to help with the crashing issue.
Try to start Anki while holding down the shift key to disable all add-ons and maybe select a different folder on export.
If there is any error message, maybe copy and paste it here.
One thing you could try is renaming your prefs21.db file in your Anki data folder while Anki is closed. It will reset remembered file locations, and may resolve your issue.