Crash to desktop on loading

On a new computer with hardly any other programs installed I am able to run everything except Flight Sim 2020. After launching I get the initial 3 screens then the background mountain image then before Installation Manager overlay appears the program crashes to desktop with no on-screen error message.

Hardware:
AMD Ryzen 7 3800X Eight Core CPU
mobo: ASUS® TUF GAMING B550-PLUS
RAM: 32GB Corsair VENGEANCE DDR4 2666MHz (2 x 16GB)]
Video: 8GB NVIDIA GEFORCE RTX 3070
Disk: 2TB INTEL® 660p M.2 NVMe PCIe SSD
PSU: CORSAIR 750W RMx SERIES

Software:
Windows 10 Home 64 Bit 20H2 (19042.630)
Graphics driver: GeForce Game Ready 457.30
Flight Sim: V 1.11.6.0_x64
DirectX 12

Already tried:
Updating Windows + store apps. Same problem on last 3 versions of flight sim
Downgrading graphics drivers
Running as Administrator
SFC & DISM
Running in different Windows account
Running other MS store free games - all work fine
I have followed the flightsimulator zendesk com article 360015879160-How-to-troubleshoot-crashes-CTDs-at-the-loading-screen

Looking at a different installation I see the window overlay it always fails to display is ‘Installation Manager’.
The only Event Manager error of relevance I can see shows

Faulting application name: FlightSimulator.exe, version: 0.0.0.0, time stamp: 0x5fa3fc26
Faulting module name: ucrtbase.dll, version: 10.0.19041.546, time stamp: 0x43cbc11d
Exception code: 0xc0000409
Fault offset: 0x000000000007287e
Faulting module path: C:\windows\System32\ucrtbase.dll
Report ID: 79dd90b3-a211-4b28-b06a-35ee6df262de
Faulting package full name: Microsoft.FlightSimulator_1.10.11.0_x64__8wekyb3d8bbwe

Note, there is no integrated graphics capability on the CPU
There is no 3rd party virus protection.

Just downgraded Windows to 2004 - same problem.
Tried clean boot - same problem.

I’ve not seen any other posts of people who have the RTX 3070 graphics card. Suspicious.

Same problem here.