This is not a bug. Please read the SU2 beta release notes.
Changes to Career/Challenge League in the Sim Update 2 Beta
Beginning with the Sim Update 2 Beta, Career and Challenge League will have separate progress and leaderboards from the live build.
This means Career mode progress in the live build will not carry over to the flighting build, and vice versa. In addition, Challenge League in the flighting build will have a separate leaderboard from the live build.
Making Career and Challenge League progress separate in the flighting build allows us to test additional changes and fixes that cannot be tested in the live build. All Career specializations will be unlocked by default in the flighting build to allow participants to preview changes that might not be available (based on Career mode progress) in the live build.
There is also a pinned post about this in the beta forums here:
Thanks,
MSFS Team