occasionally there's a glitch where after I deploy my armies and move to the attack stage it still thinks I'm trying to deploy.
Were you holding down the Mac version of ctrl+click? Ctrl+click deploys in the attack/transfer mode and is a feature.
There's a chance that you got booted instead of surrendering. You can be booted from a game if you've taken to long to make and commit your orders. Boot details can be found at https://www.warzone.com/wiki/Booting
Are you able to describe how to reproduce the auto surrender?