I tried something different this time when trying to repair .NET and it appears to have worked. I will try this again on another device to confirm.
I disabled .NET on build 18362.175 by uninstalling all of the default enabled .NET Features, using a DISM command (including the /Remove option).
I used DISM to attempt to add NetFx3 as a Windows Capability. This restores .NET to the list of Capabilities, but not to the list shown in optionalfeatures.exe. This is the same as it behaved in the past also.
I then uninstalled the May 14, 2019—KB4495620 Cumulative Update for .NET Framework 3.5 and 4.8 for Windows 10, version 1903. After downloading it from Windows Update Catalog, I reinstalled the .NET KB4495620, as Windows Update did not appear to immediately find it.
Then I ran the long DISM command to enable all of the disabled .NET features that was mentioned in an earlier reply:
DISM /Online /Enable-Feature /All /NoRestart /FeatureName:Microsoft-Windows-NetFx3-OC-Package /FeatureName:Microsoft-Windows-NetFx4-US-OC-Package /FeatureName:Microsoft-Windows-Client-EmbeddedExp-Package /FeatureName:Microsoft-Windows-NetFx3-WCF-OC-Package /FeatureName:Microsoft-Windows-NetFx4-WCF-US-OC-Package
After that, .NET was again looking normal in optionalfeatures.exe and the various features showed as Enabled in the command:
DISM /Online /Get-Features /Format:Table