So, the point of this blog post is to try to spell out that we've fixed this.
Meanwhile if you see ANY unable to decrypt errors, PLEASE submit debug logs on both the sender & receiver, and we will jump on it aggressively.
In terms of threads: yes, the stuck unread notification bug(s) were a disaster, but also fixed last year. Behind the scenes, 2023 was an absolutely awful year for Matrix & Element along many axes, c.f: https://matrix.org/blog/2023/12/25/the-matrix-holiday-update.... Sorry that you got caught in the disruption.
See also https://cfp.matrix.org/matrixconf2024/schedule/ for all the other Matrix stuff happening over the next 2 days :)
Last time I tried the threads-feature (with Element) maybe a year ago, it was still in beta.
Anyhow, if you're ok with Slack, then you probably could have just not use E2EE at all and avoid issues related to that?
my experience is based on regular old element clients and my own server and will be moving to x and sliding sync probably at the end of the year
We ran Element for our dev team for 6 months and had to give up because frequently a person would just not be able to decrypt a message, warnings would appear but there was no way to solve this. So literally people where missing messages and just having to ask people to post the message again (because there was no way to request the keys be sent). It was a complete disaster and only got worse over the 6 months.
The notifications icon was a mess too. You would frequently see the "unread messages" indicator for a message that was in a thread sub conversation somewhere, even though all the messages had been read. So again people were missing messages.
Despite numerous people begging for threads to be disabled while Element fixed the bug, they refused to put that option in.
In the end, we had to give up and just move to Slack. I really want Element/Matrix to work. I feel like we need it to work, but the lack of support and understanding from the development team would make be warn people to not use this in a professional/day job environment.
That being said, I'll defo be trying it out again personally with the hope they've listened to the community and fix these important bugs.