The odd thing is that the loudspeaker symbol is greyed out and the cursor jumps over it. Presumable you have and can contro sound on the radio and media. If so It suggests that it is truly disabled in Navigation or somehow not available and not just muted.
The Linguatronic command to turn voice output on or off is listed in the Online manual/guide as shown below.
I haven’t checked but if the sound were turned off by Linguatronic, you would expect the mute symbol to appear, i.e. loudspeaker with a bar through it, but still be able to turn the sound on or increase the volume manually. If the Navigation system prevents you from doing the software is being too clever for itself.
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