Ok, so I've been mission farming for months now. I love it. So since I use it so frequently and have become kinda an expert on it (which isn't saying much, it's pretty much just knowing how high a pet's stats have to be to take the mission then waiting up to half the day) I want to know if there have been some sudden changes or if it's just me.

The first change came a while ago, maybe as far back as January. When doing the level 50 Legendary mission in the Umbra forest, my odds of success with stats over 800 moved from always giving me 2 exceptional rewards to OCCASIONALLY giving only one. I assumed it was the developers making the system harder (which I don't blame them for, it was pretty easy and probably better for the economy of the game).

The bigger problem came a few days ago. From what I thought I understood of the mission system, the available missions refresh every hour and the available ones are assigned randomly (which meant you could have the bad luck of having the mission you already accepted still be offered and thus locking you out, or be really lucky and have the mission you just completed be offered again). But now, it seems like the same missions remain present over and over, even after time changes. Is this another change to missions to make them more difficult or am I just imagining things?

Iunno, my rewards haven't dipped. I occasionally get the regular 1x exceptional satchel, like...once every 1-3 weeks?
I've been doing the 6hr and 12hr missions so often, that my 2x successes are way greater than the occasional 1x. xD

As for your 2nd question, I've seen that happen as well (like aw shucks hafta wait another hour), but I chalk that up to bad luck. It would be unreasonable for the admins to program that...

Then again, that's my opinion. Have you pinged/PM Krinadon about this? He'd be the one that adjusts rates of missions and their successes. But personally, I think it's all luck. ;w;

Just keep doing what you're doing as a general comment; you're on the right path.