After plunging through tons of ridiculous malware pages I found this site: https://kb.paragon-software.com/article/268
It appears that under certain circumstances the service WebClient has to be running in order for rclone mount to work propery.
However, the service is not running on my work PC, so this is probably not the entire story.
Anyway, it resolved the issue on my private computer.
Thanks again for the help!