LogCat is missing the filters options

There is a way to make it appear. Just click the "Event log" label in the bottom-right of AS.

But it may will miss again in some case... I guess whether it's a bug of AS.

This bug is still existing in Android Studio 3.5 the lastest stable version, I got it just now(08/26/2019 3:13PM).

Had this problem on Android Studio 3.2 Beta 4 (Windows 64-bit). Toggling 'Floating Mode' on and off again made the filters reappear. Bit faster than exiting Android Studio if you're lucky enough.

Had the same problem.

Exit and restart Android Studio and it should be fixed.

Interestingly, the first time I tried to re-open Android Studio I got a crash. But the second time it worked fine. Perhaps there's a bug somewhere.