Sophos Transparent Authenication Suite 2.5.1.0 STA service wont start

I have installed Sophos Transparent Authenication Suite 2.5.1.0
Where i have followed the guide online on how to configure - https://community.sophos.com/kb/en-us/133531
We have 3 sites with 3 x Sophos XG. 1 site is already running fine with STA.
The other 2 sites (with their own DCs) cannot start the service. User is a domain admin and has logon as local service right

The error i get in the event log is
Faulting application name: stas.exe, version: 2.5.1.0, time stamp: 0x5ddc0897
Faulting module name: stas.exe, version: 2.5.1.0, time stamp: 0x5ddc0897
Exception code: 0xc0000005
Fault offset: 0x00007532
Faulting process id: 0x18cc
Faulting application start time: 0x01d5d231e88fa7b9
Faulting application path: C:\Program Files (x86)\Sophos\Sophos Transparent Authentication Suite\stas.exe
Faulting module path: C:\Program Files (x86)\Sophos\Sophos Transparent Authentication Suite\stas.exe
Report Id: 2645431d-3e25-11ea-8113-000c2911f4e3
Faulting package full name:
Faulting package-relative application ID:

I've already logged a case with Sophos - which has been unhelpful thus far.

Any ideas anyone? Thanks in advance