After adding more content to my game the engine bugs out

During a session my goal is to improve my game as much as possible. I add sprites, add code etc. But I’ve found a trend using this where after too much editing the changes I make will simply make no difference in the actual game. I can see them in the editor, but not when testing. It starts off small. “Okay I’ll need to rotate this face on a sprite so it is upright in the game. Cool.” And then plunges into a “I wrote new code. Nothing is happening… Let me test out if I can delete a new object I’m about to make when it collides with another new object I’m about to make… No I cannot even do that.” Is there a solution to this besides creating a new scene?