@DustyArmstrong
Hi Dusty,
I set mine to concurrency = 1, then set the config backup to be 1/2 hour before the VM backup, and had no further issues.
Just a guess, but space the execution times out so the jobs have no overlap in execution times, and set concurrency = 1.
I use the rovinray docker image, with stock defaults except for allowing NFS mounts. I use Portainer to manage docker, and can send my template file (same as docker compose).
All the best,
Mark