Something I've noticed is that when going through my officer assignments in space, when I open my inventory and go to the replicator it kicks me out of the mission I'm looking at, the officer I'm talking to, and boots me to the sector mission list.

That's REALLY annoying if you're trying to replicate supplies for a particular mission. Is there any way that can be stopped? Thanks.

Someone explained (possibly even Heretic) that the Shipboard officer assignment UI and the Replicate UI are technically the same type of selection UI and because of the nature of those types of UIs only one can be open at a time.

Short answer, it is a limitation inherent to the game engine.

Nothing special, you will find many annoying things like that when you look around, for example open Mail while exchange is open...when you close the mail exchange closes, too. Funny bug when you change from buy to sell tab and then back the search timeout restarts. Or try selling stuff to a merchant with inventory open and resort some stuff in inventory, sometimes both windows freeze and you have to hit ESC several times until you can do anything. Hell will freeze before this gets fixed, don't waste time on complaining about it.

That seems...

Really stupid. Why would those interactions be using the same mechanic at all? Why not use the ones that the other windows use... Or at least kick it into the personal tab when you open the mission like it does when you're inside your ship.

I don't know - and I'm going on a sketchy memory, so take it with that caveat.