USB Recording problem XDJ RX2

Hi, Yesterday i tried to make a USB recording on my new XDJ-RX2. I doesn't work very well. This is what happened with two seperate Sandisk 32 GB USB sticks:

USB stick 1:

First attempt: after aprox twenty minutes (and 255 mb) the recording stopped. 

Second attempt: after aprox. twenty minutes (and 171 mb) the recording stopped.

USB stick 2:

After the record there is a folder on the USB-drive (Pioneer rec) but there is nothing in it..

The master record (red) light is blinking fast and constantly.

So, how to solve this? One of the main reasons i bought the RX2 was the possibility to record directly on USB..

Both sticks are formatted DOS FAT on Mac

And: how do you stop the recording? Stop the track and unlock the UBS or stop the track and then stop the master record?