Lightroom unable to back up the catalog

I encountered a very annoying issue after upgrading from lightroom cc to lightroom classic.

The situation is this, I have a network drive mapped on my windows machine (connected via samba). during the lightroom CC days, i have always backup-ed my catalog into this network drive after i quit lightroom with no issue. However after I've upgraded to lightroom classic, it keeps telling me that it is unable to backup, and to check the folder permission and if it has any capacity left. I've checked that I have still ample storage capacity left and I've even set my folder permission to 777, but I'm still unable to back up anything via the new lightroom CC. Anyone encountered a similar problem as me and has any idea what is happening?