I have the same issue, reloading does not work, alt tabbing and switching the video settings do not work. only restarting game works. I have notice when this bug appears that when I close the game, it crashes.

I have also found this bug, I believe it originated for me in the Diplomacy screen, while trying to make multiple demands in the same turn of different AI empires.

Saving, then reloading the game entirely, seems to have solved the problem.

I had the same thing happen to me when I made a demand in the diplomacy screen and the AI accepted it.

Yep I am getting this as well at the moment - not a clue what triggered it for me I just found that suddenly I couldn't click on anything and moving armies was impossible.

I managed to play most of yesterday with only a couple of instances of the issue.

I think it might have something to do with interrupting 'Avatars' as they do their response animation/speaking to a demand you've made. So long as I wasn't being hasty in the diplomacy UI I didn't encounter the issue

I experienced this today after vassalizing a civilization.  There was a long delay before I could scroll the map at all.  After reloading it seemed improved, but the inabiltiy to scroll the map occurs sporatically.  It's limiting my ability to play.

Same here, defo something to-do with the diplomacy screen as stated there for me too.

it only happens to me after I open the diplomatic screen and I can only reopen the diplomatic screen I have to restart my game for the screen to work. Not even a reloading of an older save fixes the problem T_T

I get this at times when trying to scroll on the map with left click. 
I also think this is related to a different bug I reported here before seeing this thread: Game Broke on Alliance Proposal

Same bug here. Noticed it when another culture had a grievance with me. Couldn't click accept or refuse (Like I'd pay 100 bucks not to fight. Get real haha). Thought it was just UI elements affected, but couldn't click to move. Oddly enough, I could select an army by clicking beneath the unit on the tile itself, but couldn't perform any actions

Same thing going on but it's been plaguing me a lot today. My only resolution when I lose control of the screen is to exit and restart the game. I've seen it happen on the Diplomacy screen most often as several people have mentioned but I've also encountered a couple times on events as well. Most recently, my religion choice right after moving into the Ancient era was the cause of this problem so it's not exclusive to the alliance proposal. It just seems that particular event really doesn't play nice.

Same bug.  Sometimes if I use the PageUp/PageDown key to zoom in as close as possible to a unit, I can left-click to select it. But it won't let me right click to properly move a unit.  When I left click to move a piece with the mouse, it select hexes other than the one the mouse is hovering over.  The only way to fix the problem is to completely exit the came and restart it.

The same phenomenon occurs.

I think the request window in the diplomacy screen is left in the center of the screen in a transparent state. As a result, only the area around the center of the screen becomes unclickable.

For example, I was able to operate the settings screen without any problem, which is located in front of the transparent window.

Loading the data does not solve the problem, only restarting the game does.

However, even after restarting, the problem recurs after opening the diplomacy screen several times.

Will a new game data solve the problem?

I'm sorry, but my English is not very good, so I'm using Deepl to translate.

Translated with www.DeepL.com/Translator (free version)

I can add another instance of this. I wasn't sure if it was because I was in borderless windowed mode or not. It did seem to happen right after a diplomacy screen as well. I was no longer able to zoom, select, or do anything else with the mouse on the map. The menus however worked fine and I was able to save the game. I do not yet know if reloading will fix it.

Adding my name to the list of folks with this issue. Also occurs for me in the diplomacy screen, as mentioned by others. Definitely seems like a transparent layer blocking inputs. Very, VERY frustrating bug, this one.