Rename the Directory where MSFS is installed (for me it's C:\Users\%USERNAME%\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe), then click Uninstall in the xBox App, Change the install Dir back to original name, then click Install in the xBox App. Took just over 2 minutes from start to finish and I now have 1.18.14.0 installed