I can confirm that I have had the boost gauge not working on one single occasion. For no reason that I am aware of the gauge didn't work at all during a 300 mile trip. I assume that the boost function was still operating since the "Voyager" screen would show the relevant boost level.
When starting up the following day the boost gauge was working as usual.
I don,t know what caused the malfunction and because it only happened on one occasion I didn't do anything about it.
I know this is not of much use to you - it was just to tell you that I did have this happen to me.
Regards
The Great Dane