Issues

[Batman96]

Everytime I get a message from someone my phone automatically goes to the lockscreen for some reason...

[MochaVex]

Sounds like it could be a System UI crash. Does your phone go black before doing so?

[Batman96]

Yes

[MochaVex]

It's a known issue. Should be fixed when Beta 3 releases. Hang tight!

[user751201tmO21]

What are you using for "messaging"?

EDIT:
try this:
(phone) Settings > Apps

choose the messaging app

Tap Force Stop (lower right)

Tap Storage then Clear Cache (lower right)

[Rmosco12]

Mine does the same thing except it goes to the factory lockscreen wallpaper then back to my wallpaper I had set

[Rjmjr69]

I found a system wide cache delete stops allot of random crashes. Goto system recovery menu
I normally wipe it a few times not that it does anything different however just to be safe. Then system reboot.

[USBetaModerator]

Hello @Batman96 ,

Please navigate to 

[Settings] → [Applications] → [Menu] → [Special access] → [Optimize battery usage]
→ Change the filter (upper left corner) to "All"
→ Find the message app , and change the option from "ON" to "OFF" to exclude the app from "Battery optimize target".

You may also do the same for any web browser apps you are using,

Regards
One UI Beta Team