DA7217 Playback

Hi Support Team,

I have the DA7217 Evaluation kit, and I have the following problem:
First, I set up the codec and the audio paths via I2C. Then, I repeatedly play a tone via I2S.
The first few times I play the tone via I2S, it works as expected. However, after playing the tone multiple times, the codec also plays another tone with a high frequency and increasing volume.
After multiple playing a few more times, the high frequency tone gets way too loud. Also, at this point the codec starts using more current (0.03A instead of 0.01A), even when I am not playing anything.

My setup:
IO voltage: 3.0V
PLL: bypass mode, MCLK is only applied when something is transmitted via I2S.

I2C settings (registers from 0 to 255):
[0x1, 0x0, 0x0, 0x0, 0x23, 0x39, 0x4, 0x0, 0x0, 0x0, 0x0, 0xaa, 0x2, 0x0, 0xf, 0x35, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x80, 0x80, 0x0, 0x0, 0x80, 0x77, 0x77, 0x7, 0x40, 0x0, 0x0, 0x0, 0x48, 0x3, 0x48, 0x3, 0x0, 0x0, 0x0, 0x3f, 0x3f, 0x0, 0xff, 0x71, 0x0, 0x0, 0x0, 0x0, 0x0, 0x9, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x7f, 0x0, 0x0, 0x24, 0x0, 0x50, 0xa3, 0x31, 0x11, 0x1, 0x74, 0x1, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x4, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x20, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x40, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x4, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x8, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x1c, 0x90, 0x40, 0x0, 0x0, 0x1, 0x14, 0xb, 0x60, 0x4, 0x0, 0x0, 0x0, 0x12, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x55, 0x15, 0x0, 0x40, 0x0, 0x2, 0x1, 0xb7, 0x4d, 0x0, 0xf0, 0x11, 0xe, 0x0, 0x0, 0x80, 0xf, 0x0, 0x40, 0x1, 0x0, 0x0, 0x40, 0x1, 0x0, 0x0, 0x80, 0x80, 0x0, 0x0, 0x7, 0x7, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x8, 0x0, 0x0, 0x0, 0x80, 0x3, 0x80, 0x3, 0xa8, 0x3b, 0xa8, 0x3b, 0x0, 0x1, 0x44, 0x0, 0xb, 0x0, 0x0, 0x0, 0x8, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x40, 0x0, 0x1c, 0x0, 0x1, 0x2, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x6f, 0x6f, 0x6f, 0x6f, 0x6f, 0x6f, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0]

How can I fix this?

Another question:
In the example scripts that came with the evaluation board, in DAC to HP.txt I see the following lines:
WRITE DA7217 0xCC 0x01 //MIXOUT_L Enable
WRITE DA7217 0xCE 0x01 //MIXOUT_R Enable
However, the datasheet says that these bits are reserved. Is this a mistake in the example script, or in the datasheet?

Regards,
Abel