@itachi 4.23.0 probably has bugs that need to be fixed with its first patch. Generally I try to wait until at least the x.x.1 release or further depending on how many new features they put in place. I've noticed development of the engine and community participation has slowed a lot over the past couple years. I wouldn't be surprised if there's still some weird bugs that can be difficult to sort out until some of the very experienced or big projects come across it.
I think they changed the method player controller takes control of a character. I remember someone posting about that. I'm not quite sure what they changed. In my experience, replacing the nodes sometimes works. Other times the whole method of client or server side controller stuff needs to be reworked. Usually it just takes a bit of tinkering. Luckily this part of the menu system is very basic and really just there as an example. Most of this project's work is in the UMG and online sessions part.
It could also be the UMG Controller plugin. So many people have been having problems with it, that I'm considering removing the plugin. I'm not sure if anyone knows how to fix it. A quick glance at the plugin's forum page will show you the various issues people report. Personally, it's always worked for me but people are reporting problems. I've not tested it further outside of my own personal setup. https://forums.unrealengine.com/community/community-content-tools-and-tutorials/58523-gamepad-friendly-umg-~-control-cursor-with-gamepad-analog-stick-easily-click-buttons
For example, like maybe 10 versions ago they changed some stuff with physics and I had one heck of a problem getting physics actors to ragdoll again without weird problems. I had to completely rework how I did that. My guess it probably just needs the node replaced possibly.
Thank you for going through this and seeing what things are the hangups on this release. I've been waiting (I guess fuitlessly) for the new online framework to come out since I don't want to re-invent the wheel. But I guess it won't come out till next year now. I thought it'd be out in July 2019.
Goodluck with your project! Sorry I can't be of too much help.