I recently upgraded to the newest version recently and noticed when I select a pattern which is not in the pattern playlist (along with the "Follow Song" flag unchecked) and try to play it with F7, it plays the pattern currently selected in the pattern playlist instead.
EDIT: It turns out if I click a "blank" pattern in the pattern list (i.e. "---") and then select an unlisted pattern, then I am able to play that unlisted pattern. However, if I select pattern which is on the playlist again, I have to "unselect" that pattern again (by selecting the "blank" pattern in the pattern list i.e. "---") before I can play unlisted patterns again. Kind of annoying, not sure if this is a bug in this new version.
It sounds like a bug to me, but I'm not a developer.
In any case, its always allowed to post these kind of things in our issue tracker. If it appears to be not a bug, then closing it is easy. This way, others who find out the same thing can search for it at the correct place and read the developer commentary about it.
You can find the issue tracker here (http://bugs.openmpt.org/) and also at the top of the forum.
Yes, this indeed seems to be broken since OpenMPT 1.24.03.00, but I will probably not have much time during the next few days to look at it, so please repost the bug on the issue tracker so that I won't forget about it.
Seems like I didn't forget and fixed this now. You can grab revision 5363 or newer from http://buildbot.openmpt.org/builds/ in about an hour, this should fix the issue.