Hi,
Any news on this issue?
I think it's a C3 engine problem, not even the Greenworks plugin.
I upload a prologue demo of my game a couple of years ago: https://store.steampowered.com/app/1627820/Universe_For_Sale__Prologue/.
In this game, the Steam overlay in general works just fine pressing tab. It's not flipped and I used the stable r260 version of C3 and Version 0.52.0 of the Greenworks plugin to export it.
Looking at this old result I tried several uploads on private branches on Steam and I came up to the conclusion that the error is in C3 (don't know which C3 version exactly broke the stuff).
I tried things like using the 0.52.0 Greenworks plugin on the latest C3 (r368.2) and it's still flipped.
The only thing that works and fix the problem is to revert my project to the r260 build and using the 0.52.0 Greenworks plugin, then export and upload on Steam.
Unluckily r260 it's an old version of C3 and not supported anymore, so I don't feel confident in uploading my game to public with such an old version.
But many users are reporting this issue so it would be nice if it could be solved.
I hope to bring the discussion a bit closer to the point but the main stuff I want to bring is that C3 can influence the way the Steam overlay is rendered.