NSProgress NSProgressFileURLKey not working with sandboxed items

#define KdownloadsPath NSSearchPathForDirectoriesInDomains(NSDownloadsDirectory, NSUserDomainMask, YES).firstObject

_downloadedPath = [KdownloadsPath stringByAppendingPathComponent:fileName];
 _downloadingPath = [_downloadedPath stringByAppendingString:@".download"];

NSDictionary* info = [NSDictionary dictionaryWithObjectsAndKeys:
        @"NSProgressFileOperationKindDownloading", @"NSProgressFileOperationKindKey",
        [NSURL fileURLWithPath:_downloadingPath], @"NSProgressFileURLKey",
        nil];

self.progress = [[NSProgress alloc] initWithParent:nil userInfo:info];
[self.progress setKind:@"NSProgressKindFile"];
[self.progress setPausable:NO];
[self.progress setCancellable:YES];
[self.progress setTotalUnitCount:_totalBytes];
[self.progress publish];

(updating the progress indicator happens elsewhere)

I'm creating an NSProgress object to show a progress indicator underneat a file in my Downloads directory. The entitlements includes com.apple.security.files.downloads.read-write.

The indicator does not show when NSProgressFileURLKey points to the sandboxed file path, e.g. /Users/mdbraber/Library/Containers/com.mdbraber.TestApp/Data/Downloads/Test.pptx.download. It does work when NSProgressFileURLKey points to the direct download location which the sandbox links to e.g. /Users/mdbraber/Downloads/Test.pptx.download

Is this a bug or should I use something else for NSProgressFileURLKey to make this work?

NSProgress NSProgressFileURLKey not working with sandboxed items
 
 
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