Uninstalled 3rd party antivirus, and re-downloaded - No joy.
Checked dxdiag, DirectX12 is installed and up to date.
Confirmed that version 2.5 still launches as intended.
Reisntalled 3rd party anti-virus (Immunet - ClamAV based)
Confirmed version 2.5 still launches as intended.
I suspect an issue with the release that is available for download here.
Edit: Also tried running as admin in both states
Edit again: Also checked file properties, it is not blocked.