Hi denali,
If you mean the master cylinder's adjuster screw inside the brake lever, it's possible to screw it too far inward, at which point it can completely disengage from the nut. That's beyond the recommended adjustment range (maximum is with the end of the adjuster screw flush with the nut, that is, all the threads still engaged). It's difficult but not impossible to re-engage those threads (that's how Magura assembles the lever).
If that's what you're seeing, it means the brake shoes need a washer or two to bring them closer to the rim, rather than using the adjustment at the lever. Just add a millimeter or two to each side, between the brake pad holder and the caliper arm. Might be able to simply move a washer from outside the arm to inside the arm.
Here's Magura's manual with pictures:
https://www.magura.com/...-tt-1/downloads.html Click on "Workshop manual RT brakes" to download the PDF.
Illustration H2 (on page 9) shows the adjusting screw.
The written instructions are on page 21, called "Setting the pressure point."
Cheers,
Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)