ok, so I had 2 mining missions queued up at the same time. I mine the first objective and turn it in. I go to sell the extra ore that I mined but the station I turned the 1st mining mission into has no market. The 2nd mining mission's rock just so happens to be in the same system as my 1st mission's turn in so I try to fit in the 2nd special rock requirement anyway, but fail because my remaining cargo is to small. I go to a station that has a market and sell all of my ore and go back to the 2nd mission's special ore. I then notice that my "harvest mission is complete" even though the amount of ore in my cargo bay is less than the mission requirement.

I think the game counts how much special ore you mined and not how much you are holding. The glitch doesn't appear to have any grand exploit or anything, just kinda funny to accidentally catch a minor blooper. lol

ya, you still have to match or exceed the mission number inside your cargo, this minor glitch doesn't override that. It's just a simple misfire notification bug caused by doing part of an exaction, selling that part and coming back to mine again.
With making new content, fixing bugs that actually cause problems and taking feedback from players I get would guess that this notification misfire that harms nothing is of low priority, after all, gotta build the game before you polish it :)

um... no. *match* or exceed.

Now that I think about it you don't even need 2 mining missions to do this. Just get one, mine a single cycle that doesn't finish the mission, sell the ore and come back and this glitch will still happen.
At this point you are doing the glitch on purpose, just pointing out that it can work this way.

I believe the mission progress should be predicated upon the amount of viable ore in the cargo hold, i.e. implement reactive state, and not upon a naive incremental counter of the amount mined, as the player may expend some of it for other reasons.

Glad to see that you have internet back.

That is exactly the point I'm trying to make. Thank you. :)