Thank you for the advice. I think I found a different solution by following this tutorial on paused and main menus: Unreal Engine 4 Tutorial 15 - Creating a Main Menu & Game Over Screen [1/2] - YouTube
From what I could find, the issue had to do with a part of my level blueprint where I was switching the input control to the menu only and the Set Show Mouse Cursor was somehow interfering with the input when I selected restart. I was able to get it working by using the following in my level blueprint:
And removing the Set Show Mouse Cursor and Set Input Mode Game Only from the Game Over Menu (from my original post)