Searching Phone with Contains - Doesn't return all results

Searching Phone with Contains - Doesn't return all results

I'm searching our database by adding "criteria" phone (not "work phone" or "home phone") and "contains"  3379.

I get two returns, but one candidate who I know has a phone entry that also matches this (it's not "work phone" or "home phone") doesn't show up.

Is there a reason why searching for a partial string with in the phone criteria doesn't return all results?

(See attached image).