We released our app (phased release) with support of iOS 12 that was built by Xcode 10 GM yesterday morning, and still can't see crashes in Crashlytics tab:
However, we found amount of all crashes in Launch status for this version of the app:
You might have a “Missing dSYM” alert in Crashlytics, asking you to upload your dSYM files for that release. Or go here and click on your app, then click on "Missing DSYMS" tab to see if you need to upload any.
Here's a Fabric/Crashlytics doc about it: Missing dSyms
I recently added some missing dSYMs and then was flooded (in email) with several crash reports that had accumulated. (I had always thought I'd get the email notices of crashes regardless of dSYMs, so I suspect they changed their behavior recently).
In fact, I just looked at your second screenshot where Crashlytics suggests you might have missing dSYMs.