There was a recent panel firmware update for Qolsys in the last week or two but I haven’t investigated the update notes nor have I tried the pairing procedure since the update to see if anything has improved. The only thing that’s “worked” for me so far and confirmed to work by a couple others as well is to unplug the ST Hub as soon as it goes offline in the app and leave it unplugged until Qolsys is done processing devices. The Qolsys panel has already received it’s payload of devices and it will chug away adding them. You may or may not see the Qolsys panel as a device in ST, I don’t but it’s kind of a roll of the dice, there were attempts I made where it did show up in ST but it’s too hard to track down why it works sometimes and not others. What I know works is unplugging the ST hub once it goes offline. If you leave it in it’s frozen/bugged state, the Qolsys panel will error out as you’ve seen.
Keep in mind the limitations of this “work around.” You can’t see realtime statuses of devices in Alarm.com but you can in ST app. The lock doors when you arm feature does work along with turning off lights. Rules work too from Alarm.com so turning on devices on motion for instance works. The major bummer that doesn’t work is disarming the panel from selected door locks upon unlock. I rather enjoyed that feature for the interior garage door to take care of house entry and disarming in one step. Because Qolsys isn’t the primary controller, I don’t think it gets device status updates directly which is why the lock isn’t telling it that it’s been unlocked directly. Since the Primary/Secondary relationship between the devices is flawed, status isn’t reported from primary controller to secondary controller as one would expect…
The joys of z-wave home automation… Good luck!