coasting but car says 0mpg

What is your question?

I have a 2015 Prius and I noticed lately that when I start driving really slow to leave the parking lot of my apartment, it used to run on EV power and my mpg meter would be high (because I wasn't really giving it any gas while in a parking lot). But now I've noticed it is almost at 0mpg for the first several minutes and its not like I'm flooring it going up a hill. What could be causing this? It has less than 50,000 miles

How long has your 2015 Toyota Prius had this problem?

a few days