title: Pre-training distilbert for nearest neighbours, doesn't return neighbours for specific words
body: <p>I have been following the implementation posted in this answer: <a href="https://stackoverflow.com/a/60804419/18705639">https://stackoverflow.com/a/60804419/18705639</a>.</p>
  <p>Whenever the word is part of the tokenizer, the code seems to be working fine. However, when I input words like 'Covid', 'IVF' ect. the model doesn't seem to find them, even though the model has been pre-trained on text that included multiple occurrences of these words. The message returned is:</p>
  <p><code>The query word Covid is not a single token in sentence []</code></p>
  <p>I have also tried using the <code>add_tokens()</code> for distilbert-base-uncased but the words weren't being found nonetheless.</p>
  <p>How can this be fixed please? Is there a way to have neighbours for these words be returned?</p>