Agreed, and I did. Of course, the thing for bug reports says upfront that they won't do anything to fix YOUR problem, but they'll look at what's going on to see if they can fix it overall. Hardly satisfying at a personal level...
No, it doesn't at all say that. It says they'll fix THE problem, which is that mission not always granting completion.
That's the crux of the problem, though. Clearly a problem, and if not the CUSTOMER SERVICE people, who should have the power to correct problems the customer is receiving?
The developers should have the power to correct the bug; NOBODY should have the power to grant you the mission completion. When the bug is fixed, you can go do the mission.
At the very least, it's bad form to use a canned message saying they investigated the problem and are unable to verify my problem or correct it.
A necessary evil of $15/month price points. It's industry-standard form for a reason.
They also suggested I check out the forums and see if other customers had advice. Pretty clear they didn't even look at what I was talking about, as it seems unlikely a user on the forum can debug my code for me

Even worse, since i did a quick search and it appears that talking about bugs or CS tickets gets your post closed or deleted...
That's what you get for doing a quick search instead of a thorough one. Bitching about CS will get your thread closed, yes; talking about a bug in the appropriate forums will not. And you'd be surprised how often the forums DO have the solution to a problem like this, although they might not for your specific one.
Then maybe they shouldn't take those categories of complaints as tickets?
They don't. There are things that can happen in missions that GMs can help you with, such as being stuck in geometry that the /stuck command doesn't fix. What they are not allowed to do is create SP, currency, or items, all of which would be done by awarding you mission completion. WHY you want it done isn't relevant. Whether or not you earned it isn't relevant. What's relevant is giving them the power to do that opens up cans of worms that eventually destroy the credibility of companies. CCP still hasn't fully recovered from what happened when their folks abused this power.
As for the developers who DO have the technical capability of performing that work doing it for you; their time is better spent fixing the bug so it doesn't happen again. When they get around to that is based on a number of factors:
1) How many people are affected by the bug.
2) How much work would be required to fix it?
3) What else might or would break to fix it?
4) Is there a workaround that is generally available to players?
Sometimes they just yank a mission clear out instead of fixing it. Sometimes they leave the bug in place because some other bug wouldn't get fixed if they fixed this one instead, that affects more people.
In this case, it doesn't affect many people, and there is no story progression blocked by failure to complete it. It's probably way, way down the list of their priorities. You can move on without it. Once they fix it, you can complete the mission in a short period of time.