Hi,
I'm not an engineer at BeyondTrust, but I can share some troubleshooting steps we've used in our environment for BT Updater issues.
Firstly, ensure that BT Updater and SUPI are up to date before upgrading other components.
Secondly, check for any firewall issues: If the BT Updater Enterprise server cannot connect to the BT Updater cloud, verify that the firewall isn't blocking connectivity. You can check this by accessing the product updates landing page: https://productupdates.beyondtrust.com/landing.html.
To receive updates to your appliance, ensure the CloudFlare IP addresses are added to the allow list of any firewall or proxy server in front of your BT Updater Enterprise instance. Previously, it was Imperva, but BT has recently switched to CloudFlare.
You could also try clearing the cache from the BT Updater client. Sometimes clearing the cache resolves update issues.
Additionally, have you tried accessing the BT Updater via the web console instead of using the thick client?
https://[fqdn]/UpdaterSettings/
I recommend reading this documentation: https://docs.beyondtrust.com/bips/docs/enterprise
Hopefully, these suggestions are helpful as a starting point. I'm not a BeyondTrust engineer, so for critical issues and the best solutions, always contact BeyondTrust official support.