I don’t know how many others have this issue, but ever since dev beta 1 I’ve been missing texts left and right. No notifications sometimes, perfectly normal notifications others. It’s definitely a bug, but I believe I found the issue and workaround.
If your phone is on mute (with the side switch), your watch doesn’t sound OR vibrate when a text message comes in. If your phone’s sound is turned ON, then your watch will vibrate or sound when a text comes in (whichever you have the watch set to) and your phone will stay silent.
So I guess the workaround is to leave your sound on, on the phone, all the time so that way your watch can deliver notifications…