Causing “Sorry, your session has expired” on checkout

Hello,

One of our clients came to us with an issue taking orders from non-members, any new orders from new customers seem to fail at checkout. We originally looked at issues with the payment gateway, but had to eventually resort to turning all plugin’s off and turning them on one by one to find the culprit.

This plugin came up as the cause of the issue, we tried rolling it back a few versions but had no luck. Is this a known issue, Are there any details I can share to get help with this?