Entering the Rift sometimes sends back to original map

[DD39C89C-1C46-4F28-BDB7-49]

After completing event: Catch Brand crystals and use them to disrupt the rift the Rift is opened and we can enter it.

But sometimes entering to opened rift - fails without any information.After pressing F it starts loading instance, but after few seconds, loading screen changes back to original map image and send you back near opened rift.Trying to enter to the same opened rift again - fails again.

If that happens you need to wait for a new rift.

So, is that some random bug, or maybe there is limit of max players to enter at the same time?

[Teratus.2859]

I think this happens if you load into a map where the boss has already been killed and the map has expelled players.

It's happened to me a number or times as well.

[DD39C89C-1C46-4F28-BDB7-49]

So, maybe there are few instances with boss.One time when this happened, I was playing together with friend who, as first, entered rift without problem - but I, right after, was send back. My next 3 re-tries to enter failed too and rift closed.