Not sure if anyone’s had this problem but I just found a good solution. Over the summer it was humid by my house and while cold crashing and lagering in my conical, my neoprene fermenter jacket got very wet and mold started growing on it. After cleaning it and wiping it was just water, mold was still visible. I then used my surfing wetsuit cleaner (Drainbo Pau Pilau Wet Suit Cleaner) to soak the jacket and then hung it to dry and the mold is absolutely gone. 
good tip!
If the outside of your insulation jacket is getting cold and condensing water then it isn’t doing a very good job of insulating.
I live in Southern California and ferment in my garage so not only was it hot, it was very humid and I had my fermenter into the mid 30s with my glycol chiller (spike internal coil) so everything was pretty moist externally. Not sure how to fight the physics of condensation. Any ideas are welcome.
You could use fans to blow on the fermenter and try to evaporate the condensation, although if you are blowing humid air it might not work very well. What you really need is more insulation so that the inside is cold but the outside of the insulation doesn’t cool below the dew point. A conical is an awkward shape to insulate, but you should be able to come up with something that would add to the insulating value of the neoprene. Look at bubble wrap, insulation batts, blown foam or some combination of those.
I use the cool brewing fermentation bag with pretty good results on my makeshift, glycol in the minifridge with submersible pump.