VNRecognizeTextRequest (recognitionLevel = .accurate) is bad at recognizing single characters

I've been using VNRecognizeTextRequest OCR, and while the accurate setting is great for recognizing words, it's not so good at recognizing individual numbers and characters.
VNRequestTextRecognitionLevel.fast works better, but isn't accurate enough for my application. Can anything be done to make VNRecognizeTextRequest better at recognizing individual numbers/characters? I'm using a small regionOfInterest, which seem like it should help Vision find the item.
VNRecognizeTextRequest (recognitionLevel = .accurate) is bad at recognizing single characters
 
 
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