ADXL375 how many data bits in fifo mode?

I'm having issues to use the adxl375 in fifo mode.

I'm using right justified data

I do get data which looks valid however, I seem to only receive 10bit of data instead of 13bit?

The range of the value I get is: +511 to -512 which is 10bit data and the sign

If I understand correct, the range of 200g/0.049 = 4081 which is approximately 12bits for the value and one for the sign thus i'd expect the actual data to be 13bit.

Any idea what I could be doing wrong. Or is this a sensor limitation that it only returns 10bit value in fifo mode?