I'm pretty sure I offered more than +0 on this, and it definitely didn't end (null)
Link to question previously in grace period:
Comment vote coloring is backwards
A new development: With no winning answer chosen, and grace period expired, the bounty notice is still there. Or is this a local caching issue? Either way it's a bug; the screenshot was definitely taken within the grace period, and was wrong. The fact that it still shows up may be related or may be a second bug