@Timboxy I'm investigating this issue, and trying to figure out what is going on... Would I be correct in assuming that you have installed MS Office / Powerpoint from the Microsoft Store?
If so, it can probably explain the issue.
As a small test, can you try to run these 2 commands in a powershell:
New-Object -ComObject "powerpoint.application.16"
And
New-Object -ComObject "powerpoint.application"
If both commands gives an error like this: "New-Object : Retrieving the COM class factory for component with CLSID {00000000-0000-0000-0000-000000000000} failed....", it will be hard to fix...
If it succeeds and list a lot of information, please post back the information here.