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.