The first step that I would take would be to run the ALM Client Cleanup and then try to connect to ALM. The Client Cleanup is available at the following address
If that does not work then i would try the following to see if from some reason the certificate from HPE has been added to the Untrusted Publishers
Please open Internet Explorer and access below path to check for untrusted publishers.
Internet options->Content-->Certificates-->untrusted publishers
If the certificate was really invalid then it would not be valid on all instances of ALM 12.21 since they are all signed with the same signature.