Joaquin,
A left shift as you describe cannot be done by any setting that I can think of. There must be something in your test data or your measurement method that is misleading.
Use a scope or set the Logic Analyzer to high-speed sampling mode instead of XCLK sampling.
Use test data that has a single 1 or a single 0 in it.
If this device supports a loopback mode, try it and see if you can receive data properly.
Connect the serial transmit data to the serial receive side and see if you can properly receive data.
Regards,
RandyP