Ya that's not typical behavior. Maybe try a F/T and leave it in the tank for a few hours with the tank covered in a towel. Obviously watch out for catching the towel on fire with the light. If that doesn't work let us know...
And it isn't all that common with retics either, but maybe it's a mouser. Happens with beepers all the time but not generally with retics. Try a mouse again too to see if it has any feeding response, then work on getting it on rats after you get a meal in it in your care.
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