.NET core is lacking so many features it's ridiculous, we've had to downgrade 2 projects recently because even MS Azure service APIs weren't supported - if you have to work with .NET avoid core and save your self the hassle - it's still alpha quality in many aspects after years since "1.0". I regret pursuing .NET career at this point, all recent developments on the platform are a joke - despite the praise they get for OSS moves. I'm moving towards frontend these days just to get away from this mess (ironic considering how messy frontend is - should tell you enough about state of .NET core/xamarin)
I've found the same, trying to do anything non trivial in dotnet core is just asking for headache after headache. Its basic things that end up costing hours in effort to get them working. Stuff you don't think twice about in .net. I really really want to use core but it just doesn't seem ready yet, sadly.
I first tried going full on .Net Core with an ASP.Net Core project with Docker and I was going to try to use Kubernetes even though we were going to stick with Windows Servers.
It was overly complicated and there were so many gotchas I found in the proof of concept that I did, I backtracked and went with the ASP.Net Core Framework (aka Asp.Net 5) using Kestral on top of .Net 4.6 and using Hashicorp's Nomad for orchestration.