TPA6139A2: Problem with gain setting resistor

Part Number: TPA6139A2

We are using the TPA6139A2 with a 3.9 kohm (1%) gain setting resistor. I have measured the resistor value to be 3903 ohm.
The gain in the TPA6139A2 should then be 20 dB. However, on our recently produced boards it does not work. The gain seems to be the default (6 dB). When I add 100 ohm resistance (totalling 4.0 kohm) the gain becomes 20 dB. This is however outside the datasheet specification (which states 2 % tolerance on gain resistor value).
We have not seen this behaviour on our 10 previously produced boards.

Component marking for TPA6139 on the old boards: 2BTG4 CHN.
Component marking for TPA6139 on the new boards: 14TG4 C5VT.

As a side note:
In the datasheet it says "Gain setting is latched when the MUTE pin is set high". This does not seem correct, the only time it is latched (as far as we can see) is at power up.
The datasheet also reference "Rfb", which I believe is a copy paste error from some other datasheet.

Regards, Jonas

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