Why do Proxmox backup tasks disappear?

Question

Proxmox

In general, the situation is this, there is a proxmox cluster of 10 machines. Each node was given the task of fully backing up three times a week to a remote NAS server.
For the second time in a month, I observe how tasks for creating backups from the Datacenter --> Backup section simply disappear.
Tell me if anyone has experienced this problem?
And yes, tasks for creating backups from the master node do not disappear.

Answer 1

single tasks?

Answer 2

what does it mean to backup three times a week to a remote one we
have a standard backup mechanism
everything is configured in the data center
there are no proxmox settings on the nodes themselves on the account of backups, respectively, they cannot disappear from proxmox