Frequent E2E “Unable to decrypt” errors when switching between devices (first message errors out, then it's OK)


I had no issues whatsoever for a long time but recently (in the last few months) I started getting E2E errors in chats where I had no issues before.

Here are the rough steps:
- Somebody sends me a message from one device.
- Then they send me a message from another device.
- I can't see the message on my desktop (element in Firefox), but when I look at the same message from my mobile (element on android) then it is perfectly fine.
- If they send more messages, then it's totally fine on all devices (no more E2E errors)

I kept ignoring that issue because after all I was able to see all the messages (at least on one of my devices), so I was hoping that it'd just go away at some point.

However, now someone sent me a screenshot (above) of them not seeing my message. All I did was this:
- Kept chatting on one of my laptops (Element in Firefox)
- Switched to another laptop (Element in Firefox again)
- The first message I sent from the other device was received with E2E error. More messages can be sent without an issue.

I did my best to find an existing ticket but I couldn't find anything. Let me know if there's any other info I can gather, although I don't think it can be reproduced every time and it involves bugging other people :)