[Potential Bug] Elder Portal Disappearing

I fought the Elder in a Shipyard-Map and died after failing the 2nd Phase, where you have to protect the Shaper. Normally you can still kill the Elder even if you fail the Phase, so I wanted to get back into the Arena to finish him.
When I ported back to the Location of the Portal to "Absence of Value and Meaning", the Portal disappeared.
I don't know if this is intended and I couldn't find any indication of that after around a 15 minute Google-Search.
I had a similiar experience with the Laboratory-Boss, but that got fixed in a recent Patch. It might be the same problem by the looks of it.