[2019] Stuck at low mastery level despite max leveling warframes, weapons, etc.

Our team took a look at your account and noticed that you've only been using Rank 30 weapons recently. If your Warframe or weapon is already Rank 30, you won't gain any more Affinity from that Warframe or weapon. When you Forma a Warframe or weapon, increasing that item from 0 to 30 a second time also won't increase your Affinity.

Please keep in mind that you'll also require more Affinity per Rank as you increase your Mastery Rank, so you won't level up as quickly each time. I recommend purchasing or building new Warframes and weapons and leveling them all up to 30 - you'll need to level a few before you achieve the next Mastery Rank!

You can learn more about levelling weapons here! https://warframe.fandom.com/wiki/Weapons