Why my mastery rank just stuck - Players helping Players - Warframe Forums
Warframe - Rank 8 Mastery Test Guide
Warframe Mastery Rank Test Guide (Rank 1 to 30) and How to Rank Up Fast
Noob advice : don't do mastery rank test while a warframe update is pending. You won't be able to do it until you restart the client, and if you click to do