I have had the volume refuse to go beyond 11, regardless of audio source. Then, other times, it'll allow me to adjust beyond 11. I can't seem to understand what is driving this. Anyone else also experience this? Any solutions?
11 is the max "talking" volume, I think. So when you have voice control or maps open, and it's telling you to take a turn or reading menu options or responding to what you said, the volume control is for that voice. All other audio stuff does not have that limit (on December 2017 hardware, which is clearly different than some 2018 hardware, given software updates that don't apply).
It wasn't until 1984 when "This is Spinal Tap" was released that going "to 11" was even imaginable (I can't be the only one who thought of that when reading your post). The Clarity's OEM speakers aren't good enough to handle high volume anyway.