Positive lookahead

If I try to use positive lookahead to search for '&', it doesn't seem to work.
(?=&)

Yet, If i use 'and', it works fine.
(?=and)

I am trying to match either '&' OR 'and' in a string.

'&' Does not appear to be a control character, so i'm mystified.

(this was using https://regex101.com/ and set to PCRE)

Does anyone know why this happens?

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