encrypted message can't be decrypted by other participant (no keys shared)
Scenario:
- Private room with 2 participants (me + other)
- I'm logged in on both element web and the L5 on byzantium with !1134 (closed) (commit 58984a05)
- sent message from L5: can read from element web, other person cannot
The other participant has 6 verified sessions (in case this matters).
Did not have chatty running with increased verbosity, so no logs unfortunately.