MP3s and the interface

Does anyone else have seemingly random luck on whether pasted-in MP3s will play in their browser?  I'm using Google Chrome in a Windows 10 environment.  When people paste-in MP3s, they show up as a line with a play button in the forum posts.  Years ago, they used to work great:  Click play, the dot moves down the line, and you could see the length of the piece listed at the end and where you were in relation to it by the progressing time at the left edge and the position of the dot on the line.

Now, for a long time (I've just been putting up with it, or opening some pieces in another tab) when I click the 'play' arrow, the piece either plays or it doesn't, seemingly randomly, and the dot never moves, plus the length of the piece isn't displayed to the right end of the line, so I have no idea how long the piece is even when it plays.

The Soundcloud link paste-ins work fine, as do the YouTube video links.

What could be wrong with my browser's processing of the MP3 links?