Wow. Comprehensive. Thanks.
Individual round-count is really much more accurate than I had expected. It's good to know that my Elite-troop knows the value of those hightech-rounds and collects them in a cardboard-box in the storage room.
AFAIR the above applies also when you reload during the mission, if the replaced magazine had any remaining shots they are stored, and the game tries to form complete clips back at the base.
Also interesting. How many times have I not reloaded before attempting a charge because I just didn't want to waste those ~500creds half a magazine would cost. I know it's greedy, but Phalanx can't afford generosity.
Finally, the game updates the whole base inventory at the beginning of a mission, that's the reason the soldiers are restocked if you do several missions in a row (as long as there's still enough ammo at the base), that is a known bug
I don't think this should be a bug at all. It makes perfect common sense.
It goes without saying that a human being has a limit as to how much he can carry. It therefore makes sense, that you can't load your soldiers with infinite rounds for a single mission.
The dropship however, is a heavy lifting piece of hightech equipment capable of circling the entire globe on one fuel tank. For the purpose of killing aliens it is your soldiers base by extension. Now fitting backup-guns into the dropship would be thinkable but perhaps a little crowded still. However, concerning small consumable items such as ammo, grenades and medpacks ... I think phalanx would be smart and capable enough to have a couple crates of refills in the dropship and have those soldiers combat-ready at all times.
From a balancing standpoint, I am admittedly a little undecided.
It could be cool having to evaluate how you outfit your team: Whether to go for secondary weapons and medpacks for everyone or alternatively for more rounds so they could easily complete a second mission. But it could also just be a pain in the butt having to bother with it, having to go back to base and relaunch numerous times and so forth.