Concurrent Builds workspaces are sometimes removed before the build steps have completed.
This is not seen on the primary workspace, only those that get "@2" etc appended.

This causes a failure on the job in question - symptoms somewhat varying depending on the process running. Generally a file not found, followed by a process complaining that its Current Working directory has gone.

Hard to reproduce, but reproducibility seems to increase with uptime from rare to more than daily.

Affects builds running on both linux and windows slave nodes. Not seen on builds running on master.
Disk space, memory and cpu availability more than adequate.