The reason I asked if you’re using OAuth2 is that what you have both described sounds like this issue:
https://forum.osticket.com/d/102248-microsoft-oauth-returning-to-homepage-without-user-logged-in/22
I can’t really help you with this (other than pointing you in the right direction) as I don’t use OAuth2 myself, and as this issue doesn’t have anything to do with osTicket Awesome it is way beyond the level of support I can offer.
I will mark this as ‘Resolved’, but you can still comment if you feel that I’ve made a mistake.
I hope you get this sorted out soon. Good luck.