{H}ypercore is working on a new TESTNET. We spun up the testnet and tried to register Pillars but @sol and I were unable to do so. Sol investigated and found a bug in SYRIUS. He reported it here and has a patch (below)
I want to make sure that if anyone wants to deploy a Pillar right now, they will NOT be able to do that with SYRIUS until this fix is adopted. The C# CLI works just fine to deploy a Pillar however.