I know this has been reported before, but I cannot find it due to every keyword being 3 or less characters

Sometimes when you have a Macro or even starting_skillbar icons in your first hotbar, and you start your world and log in, the 1st icon (melee or whatever) is replaced by the first inventory item - in this case a bag.
Without touching a thing, I /exit out, stop world, restart world, and log back in, and now the hotbar is fine.

Not sure if this is only for Macro's created, or anything. I've personally seen it with every type of icon I drag there. Macro, Social, Spell, Ability, Art, etc. Even another inventory item I have hotbar'd there will get replaced by a bag. Maybe it has to do with having 2 hotbars open? dunno.

It's a mystery, because restarting the world fixes it. Or... just the fact I log in again fixes it. No idea, because I have no clue how it gets broken in the first place.

I think we need to look at the hotbar code in general. I've seen wierd things happen with just a single hot bar, such as the first button (melee attack) get replaced with a black box, and the second icon disappearing altogether. I've not made a deal about it because I was using 5916L at the time, which we all know has some issues currently.