I suggest you keep trying or tweaking.I’m not using any representative yet I can’t link my application to my GCKey. I have been trying since eCAS showed they started processing my application on 16th November, 2021.
On my side, overseas dependent has not been able to link account as well. PA got PR some months ago.
We got the application number for the dependent in a response, after several letters to the immigrationVO, asking for them to just acknowledge receipt of the application; we couldn't link or find application with it.