https://github.com/aspnet/Configuration/blob/dev/src/Microsoft.Extensions.Configuration.AzureKeyVault/AzureKeyVaultConfigurationProvider.cs#L44

AzureKeyVaultConfigurationProvider.Load does not configure it's GetAwaiter() continueOnCapturedContext option to false. Calling this from not async code bases can cause a deadlock.

Any chance we can use this instead?

LoadAsync().ConfigureAwait(false).GetAwaiter().GetResult()