Right now when you Create a new Instance and then close the Join / Drop Portal Dialog you will see the instance you had selected before and not the one you just created. You can still select the one you made via the Instance Bar at the right.

When creating a new Instance automatically select it in the Menu so in case you close the Join / Portal Prompt it's still there for you.

Here is a video of me showcasing the issue: https://streamable.com/ofj4kk