This is such an obvious point that I thought it would have been in the Tutorial, and so far I can't find a mention of it here in the forums. How please do I rearrange my troops? I find it hard enough to move troops I have bought down into my hero's slot, but so far I have found it impossible to merge two groups of the same kind so I keep ending up with all slots full. I have the Mac version of the game. Is this a bug or is there some trick to it?
I don't think that's what the OP meant. Sounds like he's having an issue where the drop & drag isn't cooperating whether it's due to lag or whatever. I've had it too from time to time. If I remember correctly, click on a totally different troop in your army as if you were going to drag it into another slot but don't, just drop it where it is. Then go back and try the merge again. That worked for me. Disciples I did this once in a while too when trying to swap items between generals. That helped me get lucky and figure it out.
I may be wrong but as far as I know there is no mac version of Might and Magic Heroes VI. Are you sure it's not a cracked version for mac? This could create a lot of bugs (as if there are not a lot already) and many things could not work as they should.
It is definitely a bug. It's not just troops - it's quite difficult to drag anything. You can equip weapons by double-clicking of course, but try dragging and the same thing happens as with troops: they keep jumping back until finally they obey from sheer fatigue.