whoa that's super nice to know, thanks! So other than checking the "available" and "recruited" flags, did you check/uncheck any of the other flags? Did you check "deployed"? I just tried in my save and Dimitri appeared on my roaster, but for some reason is shown as "mandatory deployment" but he doesn't actually appear on the map...But in the roaster screen he functions perfectly, and he's missing in the support menu too.
So yeah it seems a bit finicky lol. But very happy to hear that you have been able to play with them without any issue