• Description: Screen freezes when I try to open a "System Improvement Finished" pop-up, as well as upon trying to assign a hero to a system. Game runs as usual, I can interact with it using hotkeys and hear a respective audio responce, but image on the monitor is "frozen". The only way to close the game is via Task Manager (it shows the game running as normal) 
• Steps to Reproduce: Happens everytime I try to open a "System Improvement Finished" pop-up (happens only with this one) or when trying to assign hero to a system.
• Reproducibility: 5/5
• Version: latest version as of 03.09.2020
• Notes: I've allready tried to update drivers and DirectX, cheking file integrity, reinstalling the game, launching the game with Windows 7/8 compatibility, using different versions of DirectX, using -force-opengl (game crashes on launch when I use this one).
• Attachments: Here's a screenshot: 

You may have the explanation in the diagnostic html files that should be, by default, in C:\Users\$yourUser\Documents\Endless space 2\Temporary Files

Those files, once for every game launch, contain info/warn/error/exception messages provided by the game engine itself and are really usefull for those situations.

So you can :

* Run your game

* Reproduce the bug

* Look into the latest diagnostic file

* Filter to error/exception levels : you should have something to explain

* If not, you may have an error stacktrace in the "Message" level

I have the exact same issue HelterSkelter mentioned and in my case it also affects the market menu (clicking it in the economy window causes the freeze) and the quests menu, including the shortcut in the upper right corner of the screen. 

I did as Galanthein suggested and checked the diagnostic files, but there were no errors there (not even stacked in the messages). No trace of anything gone wrong, in fact.