That's what I've experienced elsewhere, but it's a new system to me, so my local rep is fairly neutral. I was going to see if it would chain on to better rewards, but I don't think we'll be back any time soon. I'm Deadly, not sure what the rank on the missions were, the payout at this point isn't what's confusing, it's how they're supposed to work with these highlighted planets.
Waring systems is definitely where I'm seeing the best return, pick up massacre missions and rinse the CZs.
I guess it's too late by now, but I guess I'd reiterate my question about the mission description body was; was it actually that body, or did the mission description say something like "Trade lanes between <that body> and some other body".
I'd also add; warring systems definitely aren't the best return. I don't really know what's going on in your case here (the fact the payout is so low is a bit of a red flag for a whole bunch of reasons, tbh, but I won't discuss them here unless you're interested).
Typically the comparison is
CZ Massacre: Can't stack them, biggest payout is 40-50m for up to 90 targets, and those targets will be not necessarily tough, but massive bullet sponges, so the time-to-kill is very slow.
Pirate Massacre: Can cross-faction-stack them, biggest payout is 40m for 30 kills, and those targets will be much weaker than CZ targets, especially if you cross-stack lower rank massacres on top of the bigger paying ones.
A fairly average cross-stack will see you with about 100m credits rewarded for just 30 kills, so that's a 12:1 kill/payout ratio, assuming you can kill either target as quickly. Of course, you'd respond to this with your experience here (that you can't even find target USS), which as mentioned, either there's some info we're missing, or you've hit a pretty obscure bug which rarely happens.