Instead of fstab try to use systemd mount units to see if it makes a diff…
Also don’t mount under /home but use a different dir for mounts by the system.
Mounts done by the system are by default not accessible for normal users unless given explicit permissions on the mounted directory…
I gave up on the intricacies of mounting a nfs share in fstab - it was too difficult to get right.
I am using systemd mount units because they are lean and clean.
This is no bug - it is a misconfiguration of your mount
For you scenario you need to units
one mount unit and one automount unit
The automount unit activates/starts the mount unit when the path specified is accessed and deactivate/stops the mount unit after the specified idle time.
Use the link provided above to find samples which you just need to amend to your system.
I did try mount units, but I failed to get it working reliably - may well be down to my own lack of knowledge.
Just to be clear: the mount (with fstab) does mount reliably. And can be used without problem. Until the mount is unmounted after some idle time. After having been idle it will automatically be remounted if I then access it through Dolphin; but not if I access it throuhg - say - libreoffice. If I first access it through Dolphin to remount I can also then access the mount through libreoffice.
That’s why I thought it might be something wrong in libreoffice.