I think matrix forms a nice basis for a secure chat platform. Only the apps are not really all that good. The desktop apps are electron based and the android app is just not up to par with telegram or WhatsApp.
Restarting the Riot had helped me to see the new messages, but not the old ones (which feels to be a correct behavior in regards to PFS). The actual problem is other party didn't knew I had issues receiving their messages until I've contacted them out-of-band - conversation looked just normal from the other side (except for me writing "test test" and not replying any meaningfully).
We ended up with a decision to try Matrix again sometimes later. Like, next year.