On same sprite it acts differently every time i'm previewing it.
It's showing full animation and pause after finish (if loop is set to NO, and continue to play if loop is set to Yes), you have to manually close preview window or click inside for repeat - this is correct.
but sometimes it's closing preview window right after animation finish and doesn't matter if it's only one frame or few. Loop Yes/No is ignored too.
It happens few times for me now in r53. Closing current sprite image editor and open it for other sprite seems to fix that bug though.
btw. i tested it on same capx file from previous bug in anim preview