No sound when panning right

I have a simple project with just piano and vocal. The tracks are mono. I noticed today that when I pan a track to the right the volume decreases until at hard right there is nothing. I took all plugins out of the path and still the same.

I can import these tracks into a new project and it works as expected but I am curious as to what got fouled up.

Stupid question, is the right output of the track connected to the right input of the master? Same question with the right output of master to your audio hardware? Have you gone through and checked any pin connections to make sure it all looks good there? If you create a new track and import existing audio does the problem persist on the new track?

      Seablade

Once I deleted the plugins in the Master channel it now works properly. I guess it was the pin connections. I never took the time to look at the pin connections but I suppose I might have put a mono compressor in the master.