Backups not working

[JustaGuy]

On mine, the log shows the backup job starting, then no mention of it again.
I checked on the process about 45 minutes after it started & there wasn't anything running.
No lockfile, no temp directory, no output.

They ran fine manually.
I sure don't get it.

+++
EDIT
+++

24 hours later, they're running as scheduled.
I'm keeping an eye on the process in iotop just to be sure, 20 minutes now & it hasn't crashed yet.

 

[JustaGuy]

Apparently something's amiss causing an intermittent problem.
3 days later now & the scheduled backup is once again an issue.

This time rather instead of logging a start then disappearing off the radar, there's no sign of even a start. (???)

There should be a backup job starting here, instead the log is typical of 98% of all entries:

Oct 20 23:59:55 Bascule pvedaemon[12779]: worker 21157 started
Oct 21 00:00:00 Bascule pvedaemon[20251]: WARNING: Cannot encode 'meminfo' element as 'hash'. Will be encoded as 'map' instead
Oct 21 00:00:01 Bascule /USR/SBIN/CRON[21163]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Oct 21 00:00:03 Bascule proxwww[21110]: update ticket
Oct 21 00:00:04 Bascule pvedaemon[20251]: WARNING: Cannot encode 'meminfo' element as 'hash'. Will be encoded as 'map' instead

No lockfiles in the way, no apparent residue anywhere- just *poof* nothing.
Yesterday's is fine, and manually it runs.

At first I think I should be checking on cron to be sure it's doing it's thing...
But that wouldn't explain what happened during the one I posted about right before this one 3 days ago- where the process simply disappeared.

What do you make of this?