Trying to assign custom playbook as a default in Dynasty

Has anyone had any success with this? I created a new coach, and wanted to assign a custom playbook (that I created) as the default playbook for both offense and defense.

This way, I'd be able to set all my formation subs beforehand, and not have to make any pre-snap subs for set plays. For whatever reason, I'm unable to assign a custom playbook to my coach, so if i use it in game, I'm unable to use any of my pre-saved formation subs. Instead, I just have to use the default playbook.

TIA to anyone who can help.