Baby sandboas can do this (same with rosyboas) where they snub thawed but eat live readily. It is one of the quirks of these snakes.

Sometimes warming the thawed food up to 90 deg works. Scenting with live mouse urine can work. Sometimes, letting them get hungry enough works, though some will challenge your patience beyond belief.

I had some wonderful rosies (babies) that would not take thawed for anything but would eat live in a split second. I finally got two to eat thawed rat pinks (rosies love rats I found out, better than mice in many cases). The other snakes I gave away to a friend.
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Mark