@oumpa31 yes, it's because you didn't tick the box when backing up your config. I had the same issue.
I can't recall the exact process I followed, but from memory I fixed it by:
- creating a new CA (WebGUI > Credentials > Certificates > Certificate Authorities > Add), so that CA could be used for the self-signing process when creating the self-signed local cert (next step)
- generating a new self-signed local cert (WebGUI > Credentials > Certificates > Certificates > Add) and using the CA from the first step to sign it
I now always tick the box when backing up my config