Opening a document on webdav drive generates Javascript App missing error

I’ve been banging my head against the proverbial LO (on a windows 10 PC) wall for more than half a day now: double clicking or opening an .odt document on a webdav mounted drive (NextCloud in this case) with LibreOffice since version 6.4.x (not on 6.3.x) leads to nasty error saying that the javascript app is not installed - the document cannot be opened. It needs to be first moved to a disk drive so it can be opened. It looks like LO is interpreting the odt document as a web document and believes it needs javascript to handle it ??? Has anyone else encountered this?
Stephan