I had the same issue on my admin account seamlessly becoming inactive at random.

The problem occurred after helping our platform team testing out a new setup of another databricks workspace.
I was testing the setup logging in as a standard user and an admin user. These roles where given to me by the platform team, and after testing, they removed the roles that I was given, which somehow resulted in my other roles also being affected.

Apparently it has something to do with databricks not being able to handle nested groups in SCIM as mentioned in the bottom of this post.
The platform team changed back the groups and my account was updated as so:

Unfortunately, I don't know exactly how they did this, but I hope this helps narrowing down your problem.