Is your client not seeing anything at all when trying to connect his/her accounts to LinkMyAgency?
There are 2 possible reasons for this. And both are easy to fix.
1) It’s the wrong account
2) It’s a permission issue
When connecting to LinkMyAgency, your clients should give us all permissions that are being asked (by Google, Meta etc).
Not giving all permissions will result into a ‘blank canvas’ when trying to select an account.