HC SSF Lost my maven instance after fighting her only 3 minutes and relogging instantly to hideout

I fought her 3-4 mins and logged in last phase because of the degen and instantly logged back into hideout and then all my portals disappeared instantly.

I am kind of sad because it took me like 80 maps to farm Maven's writ and I am hc ssf so I can't just buy another one.

I had a similar experience this league with Uber elder in SC. DC'd near end of the fight with many portals left and returned to instance being closed.

It happens sometimes. I rarely encounter it. A few days ago in SSFHC I was doing a Doriani institute in temple then realised my gem was only about level 19.7. I went to run lab thinking it was a long shot that the temple portals would remain open. It took me 3 lab runs to get a lens, and the portals remained open. I don't know if these ones are more stable than regular maps or some of the bosses, or it is completely random. I assume there is a technical reason why sometimes, very rarely, they close much faster than 15 minutes.

The main one that I'm not sure about is heist. When doing blue prints, sometimes you want to stash inventory space between rooms. Usually it's fine, but sometimes the portal shuts. So there is a risk in doing that I guess.

That's a particularly bad one you've encountered, I've not had that happen with Maven before. Unfortunate, but I think it's just part of the game. It's pretty infrequent that it happens, I assume it relates to servers, but I don't have technical knowledge.

shouldnt be able to log out of fights anyway imo

It's a function that the game play has been based off and has been for the longest time. Until they do something about logging out being a form of defense, which doesn't look to be happening, since they built it in to POE2, I think it is reasonable for OP to be upset about loosing their portals abnormally.