Scanning never completes ??

[smallhagrid]

Hello Folks.
A while back I set up FFS for a backup task between a file storage location and a set of identical USB sticks.
Saved it as a batch file, set up gnome-schedule to run it late at night - tested it manually, and all seemed fine.
It is set to do this monday - friday.
All 3 PCs mentioned here run Ubuntu Mate 18.04.5 and are on a small office LAN behind a dedicated firewall device.
Everything except the backing up described below functions normally & perfectly and has done so for ~1 year thus far.

The attempted backup scenario:
The source is a partition with 4 sub-directories each containing many more sub-directories and many thousands of document files.
Depending upon that week's works, up to 100 different documents may get changed and/or added in whichever different sub-directories that correspond to the clients.
This PC is used only as a sort of 'server' from which all those files are shared via SSHFS with te other 2 office PCs.

The destination USB sticks need to be a full, exact file & directory copy of that structure.
The sticks get swapped every few days & a single stick is taken off-site for safe storage & swapped so as to stay fresh.

A while (2 weeks ??) after this configuration was initiated, the PC was found to be unresponsive with an inability to access the shared files via the LAN.

The screen showed FFS in scanning mode, and it was not proceeding.
It also would not cancel.
It was using so much resources that it had to be force stopped.
The PC seemed to be in a poor state after that, and was given a reboot.

Upon manually testing the backup once again without changing the stick, it ran without my seeing the scanning dialogue at all, zipped right through updating ~200 files to the stick & finished with errors in copying 6 JPG files that all say 'file exists'.

Thus far I have not been able to duplicate the scanning freeze manually & have set the task automation to resume in hopes to figure this out.

This trouble seems quite similar to what was reported here:
viewtopic.php?t=4653&p=15557&hilit=scanning#p15557

Any pointers and/or guidance will be hugely appreciated.

Thanks !!

[xCSxXenon]

So now it works fine? If so, I would guess a weird network glitch occurred and something locked up.

[smallhagrid]

As of last overnight it seemed OK;
I will check it again tonight & will also be deleting the offending JPG files at source & destination locations.

My goal in asking here is to help eliminate any future SNAFUs - if possible.

Thanks.