If no projects are returned by MicroStrategy these could be reasons.

1. Run License Manager and check that you have MicroStrategy Desktop and MicroStrategy Architect among Installed Products.
2. You enabled anonymous authentication. The Guest user is a member of the Public group. By default, this user group does not have access to any projects in the project source. Revert back to Standard authentication, Administrator -> User Manager -> Public/Gest -> project Access. Set the access and privileges desired for the guest login.
3. You are trying to connect to a Microsoft Access database with database authentication. Microsoft Access does not support database authentication.
4. Similar to #2, LDAP user ID and password blank would lead to no project(s) when using LDAP authentication.

Sometimes a faulty installation is needed to be repaired.

But mostly, I have found the issue to be user not given right privileges, not connecting to right Project source or metadata corruption.