Getting a good TC vape off an RDA is definitely possible. There are a lot of factors to consider though, and a few variables express the same symptoms.
The electrical connection.
I will assume the 510 threads of your mod and Atty have been cleaned off with 91%+ isopropyl alcohol. As long as it is threading on and the threads are clean, ground is good.
Make sure the positive 510 pin of your attt is clean. Make sure the 510 post on your mod is clean, and if it is spring loaded make sure the spring is working and has enough travel to make a good connection to your attys positive pin.
None of the posts on your atomizer wiggle or spin, right?
This may be a bit of a pain in the neck, but your TC chip needs to read resistance all the way to and through your atomizer to thousandths of an ohm, so every electromechanical connection is important.
The screws your Atty uses to secure the coil to its posts are actually really important as well. The screws on the mutation x v4 aren't that great for tc. They tend to amputate or mar wire thinner than 30 awg in my experience, and ni200 doesn't seem as tough to me as kanthal of a similar awg.
If you can't find grub screws wrapping 180° around the screw above the post and trapping the wire between the button head and post top will give you a better connection.
Another solution is to make small splints of larger kanthal to go through the screw post hole parallel and above/with the ni wire so the kanthal protects the ni from the screw.
As long as you have a stable connection and you have wound a good coil within your mods resistance specifications your mod can apply wattage to heat the coil with the least amount of interference.
There are two factors that cool your coil: airflow and ejuice evaporation.
The second is important because an under wicked tc coil will hit TC and throttle watts once the juice evaporates, or almost immediately if there are spots that don't contact the wick through its entire absorbancy range. So you get a tootle (no offense to tootle puffers).
Once you have you wicking dialed it is pretty much airflow and coil positioning in relation to airflow.
The mxv4 is nice because you can play around with bottom and side air flow and it has a pretty big/easy build deck, stock button head screws notwithstanding.
I didn't think it would be anything special but the derringer is great for tc builds (great for kanthal as well).