Resolved On Screen Controls Only Work One at a Time

Hi everyone! I'm moving from the old input system to Unity's Input System 1.4.4.
I'm trying to use the built-in On Screen controls (left stick and buttons).
Everything works fine when I run the sample scene.
However, in my actual game, the controls will stop responding when tapping anywhere else on the screen.
For example: if using the left thumb stick and simultaneously attempting to tap a button or use the right thumb stick both controls stop responding.
As best I can tell, I've removed all previous references to Input.touch, etc.
Has anyone see anything like this before?
Currently testing on Android.
Thanks!
-Adam

 

For clarification: the control stops responding if I tap anywhere else on the screen, not just another control.

 

Realized my problem. Since I had my Canvas and Event System in a prefab, I never got the "Replace with InputSystemUIInputModule" prompt in my Standalone Input Module component on the Even System asset.
The solution was to open up the prefab, delete the Event System, add a new Event System (UI->Event System) and finally click the "Replace with InputSystemUIInputModule" button on the new Even System.
All of the scenes using that prefab with the Canvas and Event System were able to use multiple on-screen controls simultaneously aftwards.