Permalinks behave unreliably when target hidden by pre-join-UISI-hider

[kittykat]

Steps to reproduce

1. In a room with multiple pinned messages, open the pinned panel
2. Room settings need to have encryption enabled:

3. Pick any pinned messages apart from the top one and click on "view message" repeatedly

What happened?

What did you expect?

To go to the same message every time the link is clicked

What happened?

Sometimes it takes me to the message, sometimes to another point in the timeline. I have screenshots and can share the room for reproducing the issue, but they both contain private content so please reach out to me.

Germain and I believe the issue is with encryption rather than pinned messages or timeline. This bug is probably exposed by #19231

S-Major because I can't access the room history at all. Occasional because it requires encryption to be enabled.

URL for webapp

develop.element.io

Have you submitted a rageshake?

No

[novocaine]

Can we please expand on why we think the problem is with encryption?

[t3chguy]

Cannot reproduce on a couple of fresh rooms, have asked oob for more details

[t3chguy]

I think this is unrelated to pinning really and is a side-effect of matrix-org/matrix-react-sdk#3881 hiding the backlog due to a gap in the timeline due to missing megolm sessions causing all sorts of confusion in the TimelinePanel.

One proposed solution to this is to replace matrix-org/matrix-react-sdk#3881 with an ELS-like thing for UISIs which collapses them, though this could have an effect like #11963 or #11604