For me, I would extend the song by recording a few measures of anything (preferably 'nothing' most likely) on any track.

I do this to make the 'end of file marker' further down the timeline.
This makes the file's end point later in the timeline ... again, just my work flow.
If the file ends too soon, some VST plugins (or anything else) may stop unexpectedly.
One (unexpected) side effect of this can be that a VST effect buffer starts 'emptying' when you rewind and start again, since it never got time to empty in the first place. Then you may hear a fairly loud click/glitch on hitting 'play'.

Like I said, just something to check, and part of my normal workflow when I see this behavior.

It makes sense when you think about it; if the file stops playing before the reverb/ring has stopped being sent, the sound just stops. (yeah it can be irritating)
Simply letting the song play longer sometimes lets things resolve.

I do not work here, but the benefits are still awesome
Make your sound your own!