"Compiler failed to build request" Spam when using MKTileOverlay

I'm building a weather map that shows the rain on the map. I'm able to retrieve PNG images that are used as tiles to put onto the map. I then reload all the tiles on the map with each timeframe (tile set for every 10 minutes).

I'm able to get the map loaded up and I'm able to place the tiles and reload the data for each time slot. But I'm getting a ton of spam on the console every time the tiles are reloaded.

Failed to locate resource named "sky20Grey0@2x.png"
Failed to locate resource named "sky20Grey0@2x.png"
Compiler failed to build request
Compiler failed to build request
Compiler failed to build request
Compiler failed to build request
Compiler failed to build request
Compiler failed to build request
Compiler failed to build request
Compiler failed to build request
Compiler failed to build request

Yet the images are showing on the map just fine. But I feel like it's a bit sluggish due to all the spam coming out as I'm reloading this every 0.5 seconds with a timer.

I've tried to load the data from a remote server on demand by overriding the - (void)loadTileAtPath:(MKTileOverlayPath)path result:(void (^)(NSData *tileData, NSError *error))result function. But due to the timer this can lead to the data not getting loaded fully before it switches to the next time slot of data. I therefore pre-load everything. I can then store the NSData in memory and use loadTileAtPath or the NSURL to a stored file and use - (NSURL *)URLForTilePath:(MKTileOverlayPath)path. Both cases work. But both cases have this spam.

I've further refined things such that the MKTileOverlayRenderer is reused but that didn't help. Here's the function for that..

- (MKOverlayRenderer*)mapView:(MKMapView*)mapView rendererForOverlay:(id<MKOverlay>)overlay
{
    if ([overlay isKindOfClass:[MKTileOverlay class]]) {
        if (!self.rainRenderer) {
            self.rainRenderer = [[MKTileOverlayRenderer alloc] initWithTileOverlay:overlay];
            self.rainRenderer.alpha = 0.5; 
        }
        return self.rainRenderer;
    }
    
    return nil;
}

I'm using one MKOverlay and then just reloading the tiles as needed. Otherwise there is quite a pronounced flicker. Here's that function which is triggered by the NSTimer to happen every 0.5 seconds.

- (void) updateRainFrame {
    self.currentFrameIndex = (self.currentFrameIndex + 1) % self.timestamps.count;
    if ((self.currentFrameIndex >= 0) && (self.timestamps.count > self.currentFrameIndex)) {
        NSLog (@"self.currentFrameIndex = %lu", self.currentFrameIndex);
        NSString *timestamp = self.timestamps[self.currentFrameIndex];
        [self.overlay setTimestamp:timestamp];
        [self.rainRenderer reloadData];
    }
}

In that function I'm updating the "timestamp" in the overlay which is the time slot that contains all the tiles for that time. This way my overridden MKTileOverlay can then pass the correct path for the tiles. For example for loading from a file:

- (NSURL *)URLForTilePath:(MKTileOverlayPath)path {

    return [self getWeatherTileFileURLForPath:path];
}

Or NSData stored in memory

- (void)loadTileAtPath:(MKTileOverlayPath)path result:(void (^)(NSData *tileData, NSError *error))result
{
    return [self getWeatherTileDataForPath:path];
}

But no matter which way I use I keep getting this spam and unfortunately there is no error or anything to point to why it is spamming out.

Also the tiles themselves are PNG files either 256x256 or 512x512 in pixel size.

I saw that this could be something to do with Metal but I'm assuming that's something that MapKit uses.

Very much welcome any thoughts to what could be causing this?