I wouldn't say I "regularly do," I did exclusively campaign before the freeplay stats came online (and I learned that only freeplay was recorded), so I have a basis of comparison.
I not only play Freeplay, but I've done around 15 runs of this map recently on my maxed out main... = /
I'll try it again a new character who just hit 20 though??

I don't know. I just don't understand the issues. D:

Eh, the A.I. is balls dude. Simple as that.

Right, but it's a more balanced level of balls on each team. At least that's the observation I've made.

No. In terms of A.I. Attacking team is herp-a-derptastic useless, defense is moderate to great.

And on such a painfully uneven level, your team svcks.

So I made a little progress on early launch today after acquiring the Downed Fire ability, now I just need to keep trying. I wish I could trade in the stupid cortex bomb ability I've never killed anyone with it.

I made it to 57% of the hack which reminds me...If my hack box was still planted why didn't I get a time extended?

You can sell all your points. It's only the loss of one level and it's easy to recuperate.

I also found this particularly hard, as the bot teammates don't seem to defend me when I hack my objective. I was an engineer and repaired the crane by myself, then said, "You know what? [censored] it." And switched back to my soldier class. I just destroyed every enemy in the way and had a bot hack the crane, while I covered him, since bots seem completely unable to cover others.

I tried this on m 2nd of my 3 characters he lost 1 rank, 1 level, and 1 level point meaning the coins I had spent did not come back to me in full, so the the answer to what SELL ALL does is it removes 1 of each...

Level Points 20purchased achievements > 19 level points credited
RANK 5 > 4
Level 20 > 19

Exactly Security BOTs seem to get less effective on this map and the Resistance BOTs get better

It only loses one level. You just happened to be at a level that determined your rank. Your rank rises (or drops) every 5 levels, hence why we can only get to 24.
1-4 = rank 1
5-9 = rank 2
10-14 = rank 3
15-19 = rank 4
20-24 = rank 5.

If you're level 20 and you do this, you will technically lose one level, one rank and one skill point.

You lose on skill point because you lost a level, as if you never gained that level to begin with.