Why does the recents screen close on its own sometimes?

I have a Nexus 5X with Android 8.1.0. I've noticed recently (in the last week) a problem where the recents screen will close on its own. For instance, I will open the recents screen (by hitting the square button), then start closing apps, and before I'm finished, the screen will close on its own and go back to the home screen.

I've tried clearing cache and data for the Google app and the Google Now Launcher, but I'm still seeing the issue. I've also tried restarting the phone.

Anyone know what's going on or how to fix it?

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