Can't open PT after upgrade to 2020.5.0

[clutch]

Hi,

I upgraded my main studio machine from 2020.3 to 2020.5 a couple of days ago, but now whenever I try to open PT it says the "Subscription License Has Expired" and to plug in an iLok with a license on it.

My iLok with the PT Ultimate Perpetual license is plugged in (I've tried multiple USB ports on the computer). Have tested with other DAWs which use plugin licenses stored on the iLok and they all work fine.

Ilok License manager sees the licence just fine (I've deactivated and re-activated it to the iLok just in case).

I've tested the iLok on my laptop with PT 2020.3 and it works as expected.

Trashed PT prefs, rebooted multiple times.

I've just re-installed PT and am still having the same issue.

Can anyone shed light on what my issue may be? I'm sitting here with a client unable to get any work done...

Many thanks,

Chris