I am trying to upgrade our project to 4.16.1 as well and run into problems with WidgetInteractionComponent which we rely on to enable users to click on 3d widgets in the world. Basically, non of them appear to work anymore. The problem seems to be known ( Widget Interaction Component broken in 4.16? - XR Development - Epic Developer Community Forums ) but I wanted to ask around if anybody had the same issues.
My investigation into the reason so far is that the line trace this component does (with channel Visibility) does not hit anything anymore.