Since the update to v45, Chrome seems to no longer play select MP3 files. This is not across the board, and some other MP3 files still play. Chrome v44 displayed no issues a
I'm not 100% on the specifics of this, however, it looks like some MP3s using older versions of Lame, or longer than a couple of minutes, or at high (300 <) or low (128 >=) bitrates seem to be affected. It appears to be webkit-related, as it also affects Safari users.
HOWEVER!
As a solution, re-encoding the MP3 files using 160Kbps bitrate, and the latest version of LAME (3.99.5) seems to have fixed this, and they now play normally across all major browsers again.