That is why, if MRF is not the only culprit here you should try as many other suggestions in this topic as possible in your next sim try (none of which I believe will hinder convergence except maybe switching to TETforCFD mesh, but I present a solution for that here…
There will be more convergence suggestions if you have convergence issues, AFTER we think that you have the best geometry and best volume mesh we can achieve for your needs…
Accurate results from CADA are tedious to obtain 
Check this topic out if you want to see real perseverance to got OK results…