This is kind of in a messed up state right now. I primarily use TrueNAS as storage and then to run jails for my media server. I don’t think Scale is ready yet for me, and at least 1 of my jails is broken in Core 13.0. I am reluctant to upgrade to 13.3 as I am seeing a lot of problems with jails and developers not wanting to build/maintain for 13.x.
I think the only real solution for me is to wait until Scale seems solid enough for me (see Upgrading from TrueNAS Core to Scale - #4 by dan) to upgrade. 