Hello CrashA51,
When hitting PIE (Play in Editor), as of 4.13, the viewport will no longer immediately gain focus for input and must be clicked before any input will begin registering. If you’re not clicking in the viewport before trying to use the controller then it would seem as if the controller isn’t working due to this. Can you try clicking in the viewport after hitting play and then using the controller?
It was actually a bug that the viewport would automatically get focus previously because this is supposed to be governed by the “Game Gets Mouse Control” setting in the Advanced Options for PIE. When this is turned off, which is the default, it is suppose to function as it does now. That setting was previously being ignored. If you wish to have the same behavior as previous versions, please enable this option going forward. You can find the bug report here: Unreal Engine Issues and Bug Tracker (UE-32689)