I noticed this before, relogging seems to reset the state of the settlement and make all items disappear (even in lockers you haven't raided yet). To make them re-appear again (although this will not help with the lost mission item) you need to enter SC and go back to the settlement. Because, reasons.
Frontier don't want people to be able to relog to grind mats like they do at Dav's Hope, but Frontier haven't learned that the reason people do this is because people
don't like the mat grind. So instead they've broken the game so that if you get a disconnect, or need to relog due to a bug (which there are plenty of), it breaks everything including the mission you're on.
I'm also in the camp of main game PvPers that has reached the point with Odyssey where I won't play it due to the bugs and flaws inherent in Odyssey gameplay, irrespective of Horizons/the state of PvP (which, we've heard of plenty of issues effecting Horizons as well, not least splitting the player base instancing which is devastating to the health of PvP). Specific to Odyssey that tipped me over the edge, it was running around infinitely to find the un-tradeable mats (goods and data) needed for engineering and upgrades - grinding through bugged gameplay loops to find this stuff and having to manage backpack and inventory size to fit things.
After hours and hours of gameplay, I still don't have the data I need for engineer access with no consistent way to secure its drops, upgrades consume health monitors and suit schematics at the same rate but I have 140 health monitors and 2 suit schematics, and the only consistent way to get data - which can't be traded for what you want - is to hope you get mission rewards for the data you need because otherwise you'll be looping the same settlement hundreds of times to try and get enough of the data you need.
But don't worry guys, they've made it so that menu logging
breaks the entire settlement to guarantee you're locked into this grind.
The people in the slither of vocal forum loyalists that will defend the game 'til blue in the face can have fun repeating the same 5 radiant fetch quests in a slightly different setting for the thousandth time. But I'm not going to bother with trying to draw blood from a stone for consistent gameplay in Elite, which was already enough of an effort for quality PvP in Horizons whilst Frontier treats us like the ginger stepchild, when this is what they give us - with Odyssey splitting the player base on top of it all.
Meanwhile watching other communities gutted by the mistakes - whether it's racers on life support until Horizons gets deleted, or anarchy BGS groups that have lost years of work in the space of the week following launch. But so nice there's a token thread asking for very specific issues, as long as we don't include anything from when those factions lost everything. No going back, no fixing the problem, just going forwards.
No thanks, I'm done now.