Studio not responding when confirming segments with shortcut, faulting module path ucrtbase.dll

I note that lots of people have had problems with segment confirmation causing Studio to hang for several minutes, every few minutes I have the same problem (previously with 2019 and now with 2021). I have tried every single fix recommended on here from Studio settings to removing all add-ons, from repairs and reinstalls and clean boots to completely removing my AV software but it's still happening every few minutes. My PC spec is higher than the requirements for Studio and all software, hardware and drivers are up to date and scanned with no issues. Event viewer shows faulting module path as ucrtbase.dll which is something to do with C++ redistributable as far as I can see but it appears in multiple applications.

Faulting application name: SDLTradosStudio.exe, version:, time stamp: 0xc3551d44
Faulting module name: ucrtbase.dll, version: 10.0.19041.789, time stamp: 0x82dc99a2
Exception code: 0xc0000409
Fault offset: 0x0009eddb
Faulting process ID: 0x1628
Faulting application start time: 0x01d76f170172a198
Faulting application path: C:\Program Files (x86)\SDL\SDL Trados Studio\Studio16\SDLTradosStudio.exe
Faulting module path: C:\WINDOWS\System32\ucrtbase.dll
Report ID: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
Faulting package full name:
Faulting package-relative application ID:

Any further suggestions gratefully received as I am at the end of my rope with this now.