I am using v1.4.6 (WebDAV) on windows 10 x64.
I had a folder (in root dir) named something like: _Folder Name
I tried changing the name to all caps like: _FOLDER NAME (i.e. identical name but in all caps) and I received an error saying that the location is not available and then the folder disappeared with its files. After refreshing the folder was shown again but was still inaccessible. This was only solved by locking the vault and exiting the application completely.
Is this a known issue?