Most likely, there are some restrictions on Meta related to the Facebook profile connected to Bïrch.
Please check account health in your Business Manager https://www.facebook.com/accountquality
You can also switch the profile used for ad account/ pages connection in Bïrch to a different one:
1) Make sure the alternative profile with full admin rights has been connected to Bïrch
2) Go to the Integrations page, find the ad account in the list and click the profile picture next to its name - you'll see the list of profiles that have all admin rights to the ad account and will be able to choose another profile that given ad account will be associated with: