Yes, but not to such a severe extent, I have the 2012 Prius C with I assume the same GPS and it announces around 1 minute after I start, after the GPS HAS BEEN WORKING that "GPS signal lost" then after around 20 seconds it works well from then on, BUT every time you start again it does the same thing, Toyota refuse to state it is a fault and made not mention of the issues you described, did you end up getting anywhere?