I bought both Meg's Ceramic and their Ultimate wax, both suck ! Hard to get off and does not shine like their Tech 2.0 wax. The Tech 2.0 wax goes on and off with ease and out shine both of them. Don't know how long any of them last out in the sun on black cars, but i keep my stuff clean and waxed at all times.
Likely applying incorrectly. How much are you using? You should have a very faint haze, at most, when applied to a panel. If you apply too much, it will be more difficult to remove. My neighbor was waxing his car the other day and I kid you not, he may have used half a bottle to do a car, it was THICK. I bet he had a fun time removing that... You don't need much at all.
I apply the sealant across the entire car lightly, then once completely covered, will begin to remove in the order I started with fresh microfiber. Comes right off, streak-free and without any effort. All this is done in a shaded garage, of course, not direct sun.
Never any issue with NXT, NXT 2.0 or Meg's Ceramic for me.