This issue with Metrics Explorer part of the UI is known to us. Currently, there is no fix within version 9.0.2 and is planned to be resolved in a future release of VCF Operations 9.1.x.
Workaround:
In case a user/admin typically searches for the same metrics over and over, create a metric "Group" and drag favorite metrics into that group. That would make those metrics easier to find in the short-term.