<unk> not populating

I am making a domain-specifc spell corrector (input = misspellings, outputs=correct spellings).

Is there any reason the unknown words placeholder (<unk>) would not populate by default? My model just guesses at everything for some reason. Happy to provide any code if that helps.


This very much looks like this post : Translation: unknown words replaced with one word, instead of <unk>

Thanks! I will try that out.