No , no TiBu , I have tried going through both ring-tone set up processes , 1. select from Music list directly , 2. select "other" then Music through regular ring-tone setup (Themes) . Seems MIUI doesn't recognize Music file tones as ring-tones or labels SD Card ring-tones as Music , can we copy the Music tones to our ring-tone file on System>Media>Audio>Ring-tones/Notification Tones maybe ? Kind of a hassle , it would be easier if MIUI Devs made it so we would not have to do a work around like that .
Android picks up ring-tones on your SD Card even if they are not part of the ROM , they can be folders or part of a left over ROM , I have R2D2 ring-tones and some I have DLed as mp3 and some generated by RingDroid .
They have always worked up until the last MIUI ROMs .