Variable being reset to default after being set

I've created a simple boolean variable, DoneLoading, to keep track of when a function is finished executing. DoneLoading is initialized to False, and at the end of the public function, it is set to True.

I call SetSpawnLocation() from another script, and when I print DoneLoading at this point I can see that it IS being set to True. However, when I print out the value of DoneLoading on every OnUpdate() cycle, I've found that it gets set back to false and stays false.

EDIT: After further testing, it looks like somehow, inexplicably, the Start() function is being called AFTER SetSpawnLocation(). However, in my main script, GameManager, the gameObject below is instantiated BEFORE I make a call to SetSpawnLocation(). Why would the Start() function be delayed for so long after instantiating?

Also, is there a way to prevent Start() from wiping out and resetting my variables?

 private bool doneLoading;
 
 private void SetSpawnLocation(SpawnLocation curLocation) 
     {
 
         if (curLocation == SpawnLocation.Tropical) {
             commonSprites = commonTropicalSkins;
             uncommonSprites = uncommonTropicalSkins;
             rareSprites = rareTropicalSkins;
             ultrarareSprites = ultrarareTropicalSkins;
               }
  doneLoading = true;
 }
 
 void Update() {
         print(doneLoading);
     }
 
 

I've searched through my code, and doneLoading is only referenced in 3 places: the initial definition, when it's set to True inside SetSpawnLocation(), and when I print it out in OnUpdate().

Please please someone help me. I'm going crazy here. This is happening with all non-class variables in this script - they keep being reset when the script updates.