Visual Studio code visualizers/intellisense NOT WORKING - All codes turn white

Hello! I’m kinda new to UE4 and encountered this problem.
The codes in Visual Studio should normally look like this with all those colors, code suggestions, etc.

But once I opened a copy of the project (a copy & paste of the project folder for backup), the visual studio debugging system stopped working.

The codes turned white and even when I insert random, grammarly incorrect stuff in the editor, the program still works perfectly good.

I think it must have something to do with visual studio itself. (I checked intellisense settings and didn’t find anything wrong)
Can someone help me out?