Does the tag quality problem only occur when trying to start the group? What is the warning that the group reports?
By disabling and re-enabling the opc connection, your basically resubscribing the items (and physically reconnecting, which is a fairly substantial too, it’s possible the OPC server could be completely restarting as a result of this). The question is why the values are going bad in the first place - do they get set to bad quality somewhere along the line and never come back, or do they simply never get their first value when the group first subscribes to them.
I’m not familiar with that OPC server, so I’m not sure what it supports. Since the connection shows “connected”, I doubt any failure is being detected. If it’s just a small number of tags, you might be able to get around this by simply switching your group’s “opc data mode” to “read” instead of subscribe. Otherwise, we’ll have to figure out why it’s happening in order to see if it’s something we can influence.