Hi all, I was able to solve this issue with thanks to this bug report: https://bugs.schedmd.com/show_bug.cgi?id=13217
Basically I needed to set "LaunchParameters=disable_send_gids" in my configuration and everything started magically working - probably because the controller doesn't have the local groups the compute nodes do, Thanks, Will. This email and any attachments are intended solely for the use of the named recipients. If you are not the intended recipient you must not use, disclose, copy or distribute this email or any of its attachments and should notify the sender immediately and delete this email from your system. UK Research and Innovation (UKRI) has taken every reasonable precaution to minimise risk of this email or any attachments containing viruses or malware but the recipient should carry out its own virus and malware checks before opening the attachments. UKRI does not accept any liability for any losses or damages which the recipient may sustain due to presence of any viruses.