Visitor Visa - File reviewed and referred to CPC-O due to outstanding Cost Recovery

[Chikibam]

Hi all, I applied for visitor visa for my parents in April 2023. While my father got PPR within 15 days, my mother's application is still in progress. I applied for GCMS notes and this is what it says - File reviewed and referred to CPC-O due to outstanding Cost Recovery. Can anyone explain what it means and how to proceed? I raised webforms but no luck.
We already paid the application fees.

 

[Chikibam]

Update: My mother recieved PPR last week. I submitted a webform along with application payment receipt.