I've had that happen before. I took the cover off too early and the air was too dry causing the tips to dry. After I put them back in the clear tote box they were ok. When they started new leaves they were good. Then I would leave the cover open a little bit each day increasing the opening every few days until it was off completely. Everything was fine then. If that's not it then another cause could be over or under watering, or even too much sun causing them to dry. So many "maybe's" that it's really hard to tell but I'm sure you'll be able to narrow it down.
Good Luck!

Thanks for the insight Tony. I only take the cover off once a day for around 10 seconds to let a little new air inside the plastic bin. They're also not in sun at all, so I know that's not the cause. My top suspicion is over watering like you said. It seems this is the top error with growing fig cuttings. I'm careful to only water them 1/3 to 1/2 of a shot class every 5 days or so. They are in 100% perlite so it just drains thru. One mistake I did make is the holes at the bottom of the cups are really small, so I end up with about a centimeter of standing water in the cups, although it evaporates after a few days. I'm wondering if that is the cause. Strangely I water all 8 cuttings the same and only 2 have these black tips. And some leaves on the same plants have leaves that are perfectly fine. Thanks again. Here's a pic as of today. You can see the smallest new leaf at the tip of the new growth is all black. Basically it came out black from the get go.

Yeah it sounds like too much water. Different cutting even from the same branch will respond differently to the same growing conditions. I found out that if I just ignore the cuttings they seem to do better than to try and make sure that everything is perfect. Sometimes neglect is better. I'm sure things will be fine.

I think you're right! I had to leave town for 6 days and was worried about not being around to monitor they're moisture, temp, mood, and general lust for life. Turns out they did the best while I was gone not paying attention to them. Thanks again for the info!