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CubeMX STM32F429 I2S Ext clock frequency parameter error?

Question asked by walther.tim on Oct 28, 2015
Latest reply on Oct 30, 2015 by waclawek.jan

In my design I'm using an external 24.576 MHz oscilator as I2S clock source
Acoording to the reference manual, for 32 bit frames and MCLK output:

FS = I2SxCLK / [(32*2)*((2*I2SDIV)+ODD)*4)] 

For Fs = 96 KHz, this gives I2SDIV = 0, ODD = 1.

However, in the CubeMX configuration tab this shows an error:

"With this I2S Clock (24.576 MHz), the divider value(0) is too low to obtain the desired audio frequency(96.0 KHz).
The I2S Clock must be higher than (86.016 MHz)."

I don't understand where this 86.016 MHz is coming from.
Is there something happening between the external input pin and the I2S clock generator that I'm missing? Or is this a bug in CubeMX?