Errors loading/saving .ods files on network drive

I just replaced an old HDD with an SSD. Had to do a fresh install of Windows, LibreOffice, all other software. Since then i’ve been getting errors loading .ods files (only) from network drive:

“Document file ‘<filename.ods>’. is locked for editting by Unknown User.”

If i keep trying a dozen times, i can sometimes open it. Then i have this problem saving the file:

“Error saving the document <filename.ods>. Access to X:<filename> was denied.” Then something about a general I/O error.

Again, if i keep trying again & again, i can sometimes save it.
I’m using Windows 7 (64-bit), 1-Gbps network, RAID1 network-attached-storage (NAS), BitDefender antivirus with scanning of network drives turned off (to eliminate overhead network traffic).
I can load/run/save/copy very large files with any other software with no issues.
Old XLS files seem to load fine in LibreOffice, it’s seems to be just ODS files i’m having problems with.
Loading/saving .ods files seems to work fine on the local SSD, but not the network drive.
I’ve checked the SMART info on my network drives. They check out OK. I’ve re-downloaded & re-installed LibreOffice. I’ve rebooted my network drives & router. I’ve turned off my antivirus. Now i’ve run out of ideas. HELP!

New developments: Saving .ods file to the SSD causes LibreOffice to hang for about 10 seconds, no error message though. File is 256 KB. Once i did get a file loaded from network drive, i’ve editted & saved it multiple times today without any errors. Not sure what’s going on here.

Another new development. I just installed that other open document program (don’t know if i’m allowed to mention its name) & it is working without any errors so far.

I have the same problem here, without idea how to solve that!!!