I have just downloaded iOS 11 Beta 1 to my iPhone because I enjoy testing out the betas. I've done this for quite a bit, since about iOS 9. Last year when I first downloaded iOS 10 beta, the Mobile Authenticator and Steam Guard had major issues for me, rendering them almost unusable.
Here's what I found for myself in iOS 11 Beta 1:
- Some buttons had lag working or would not work (like the Friends button), so I simply restarted the app and all worked fine.
- Sending a trade works fine.
- Authenticating a trade crashed the app once before it worked. It did that twice. One thing that may be a problem is hitting the "You have one action to complete" button, as it made it take a while to try and load the confirmations page. Going to the confirmations page without hitting that button may be better.
- Steam Guard works fine.
If you guys would like to help others out, drop a comment if you'd like, including what you found.
For clarification, I am using an iPhone 7.