Karel Create file on MD:\ not working

I am trying to create a simple logging utility and I am trying to save the data into a file on MD.

OPEN FILE dataFile('RW', 'MD:\testdata.dt')

Everything runs fine, IO_STATUS after the operations is always 0, but the file never appears on the MD device. If I change it to MC:\ it creates it on MC and I am able to copy it to UD and read it on my PC.

But I can't create the file in MD. Again, my code successfully works on MC:\, but not on MD:\

Does anyone have an idea why that might be?