Michael, if you go to Lightroom's Help menu and choose "System Info", can you tell us exactly what is listed for the second line, "Operating system: ..."? I'd like to make sure it's straight up Windows 10 and not Windows 10 N.
On further thought, I suspect strongly that you are running Windows 10 N. We made some changes in 2.3 to use Windows' native video support, and the N versions of Windows are lacking the Media Feature Pack.
Here is the output from System Info: Lightroom CC version: 2.2.1 [ 20190312-1546-e438717 ] (Mar 13 2019) Operating system: Windows 10 OS Version: 10.0 [18362] Application architecture: x64 System architecture: x64 Logical processor count: 8 Processor speed: 4,2 GHz Built-in memory: 32701,1 MB Real memory available to Lightroom CC: 32701,1 MB Real memory used by Lightroom CC: 475,9 MB (1,4%) Virtual memory used by Lightroom CC: 637,7 MB Memory cache size: 553,1 MB Internal Camera Raw version: 11.2.1 [ 159 ] Maximum thread count used by Camera Raw: 5 Camera Raw SIMD optimization: SSE2,AVX,AVX2 Camera Raw virtual memory: 26MB / 16350MB (0%) Camera Raw real memory: 26MB / 32701MB (0%) System DPI setting: 96 DPI Desktop composition enabled: Yes Displays: 1) 1920x1080 Input types: Multitouch: No, Integrated touch: No, Integrated pen: No, External touch: No, External pen: No, Keyboard: No
I see you are also on the very latest version of Windows 10 (not N), newer even than what Microsoft lists Media Feature Packs are available for. I still suspect our video changes are the issue. Would you be willing to try the latest available Media Feature Pack to see if that helps?
Sweet! Thanks for reporting back. We will try to catch this situation in the future and give a proper warning from within Lightroom. I can't explain why the Win 10 build you have would not contain this code, however.