I've also seen the "Proceed to highlighted route" message with constant recalculation when the first segment of your route is a long segment - it keeps trying to recalculate your route until you get to your route's second segment, and if getting to the second segment requires a turn, it doesn't get announced. I also noticed this happens every time you start on a longer segment. It probably happens on every first segment but is more noticeable when the first segment is longer.
Wazing the Garden State... one jughandle at a time.
AM: New Jersey, LEVEL 5
AT&T iPhone 5 / iOS 7.1 / Waze 3.7.8