I looked for "session" and "element", but couldn't find any news stories that didn't just have those keywords. Honestly, there is no reason Telegram isn't on the list either except for the fact they don't log as much info as kik does, but most messages on telegram aren't e2ee and it's very cumbersome to ensure they are.
I just feel like people think police and whoever else have some sort of omniscience, but it's always extremely obvious when people get arrested for something. Most *murders* aren't solved and it's not like we don't have increasingly better forensics, it's just impossible to know everything that happens at all times.