GDS gets an error newCert.PrivateKey' threw an exception of type 'System.Security.Cryptography.CryptographicException'|OPC UA Implementation: Stacks, Tools, and Samples|Forum|OPC Foundation

I have just downloaded the newest version of UA-.NETStandard samples (Nuget 1.5.374 & GDS Updates (#597)) and when I try to generate a GDS certificate the private key is missing.

When debugging I can see the error newCert.PrivateKey' threw an exception of type 'System.Security.Cryptography.CryptographicException'.

I am using GlobalDiscoveryServer and GlobalDiscoveryClient 

Any ideas why this is happening. It worked just fine with an older version of UA-.NETStandard samples (1.4.365)