Anyone have this problem?

russ69....I am using HDMI. I have searched through settings for an option that might help the situation and cannot find anything.
 
ghdprentice...I agree with your possible diagnosis but cannot find a way to stop the behavior. My ten year old processor I was using did not have this issue.

Have implemented the latest firmware upgrade?You should not have this issue IMO
It is like the processor , when changing channels, stop using the former audio format . Then , it is not able to set the new format ( that 
may be the same ) . You have to go back and forth for the processor
to set the audio format.
Ask you dealer or communicate directly with McIntosh.
Go to McIntosh MX123 forum 
https://www.avsforum.com/threads/the-official-mcintosh-mx123-a-v-processor-thread.3099788/

maxwave....Yes, it has the latest firmware. I agree I should not have the issue, but this is the second MX 123 with the issue. I returned the first unit and got another. I assumed the first unit was defective but now I'm thinking it may be a design flaw. I have spoken with both the dealer and with McIntosh directly and both say they have not heard of this issue. I want to keep it because I am pleased with every other aspect of the processor. I will look to join the avs forum and post the concern there. 
   Regards,
         Steven

It great when no one’s heard of (seen) something that is inplain sight.

Have you tried switching hdmi cables?  I know it sounds dumb and “digital is digital” but just today was trying everything to get a Nintendo switch console working and finally went from the cheap hdmi cable (which I know does work) to an older but very expensive at the time Monster cable and boom, problem solved.