In the Expert Settings section of the settings panel you will find a few log files, could you share them with hastebin, preferably after you get the error. Also maybe make an issue in the github repo. https://github.com/ccrisan/motioneyeos/wiki/Reporting-An-Issue
Hmm this is very confusing, unless something has changed with motoneyeos since I last used it you shouldn't be seeing the file storage system of the camera, are you sure you are accessing the corret motioneye host? Also the connecting to the windows share sounds a bit unnecessary you should probably save locally to the VM and share that folder with the host.