When I run the following command:

Find-Package -Name Microsoft.Web.Xdt -ProviderName NuGet

I get this error:

Find-Package: No match was found for the specified search criteria and package name 'Microsoft.Web.Xdt'. Try Get-PackageSource to see all available registered package sources.

The Microsoft.Web.Xdt can be found on the NuGet site, which indicates an issue with the Find-Package command

After enabling the debug log with $DebugPreference = "Continue", the command logs the following stacktrace

DEBUG: 00:00:00.8843185 System.ArgumentNullException: Value cannot be null. (Parameter 'source')
   at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.Linq.Enumerable.Where[TSource](IEnumerable`1 source, Func`2 predicate)
   at Microsoft.PackageManagement.NuGetProvider.NuGetRequest.GetPackageById(PackageSource source, String name, NuGetRequest request, String requiredVersion, String minimumVersion, String maximumVersion, Boolean minInclusive, Boolean maxInclusive, Boolean isDependency)
DEBUG: 00:00:00.8844229 Completed iterating for 'Microsoft.Web.Xdt'.
DEBUG: 00:00:01.1371486 unmatched package name='Microsoft.Web.Xdt'

It seems that the error goes away if I add a wilcard at the start of the package name

Find-Package -Name "*Microsoft.Web.Xdt" -ProviderName NuGet

However, this is not a good solution as it might return additional non-relevant packages.