
I finally got to the bottom of this problem - visiting the dealership and talking with a technician. I didn't see anything about this in the manual, but there is actually an option on the radio to chose how many sets of presets you want to use. You can actually select one or more of the 6 sets of presets to be available. The intent is, I think, that you may only want to have, say, 3 of the 6 sets in use - meaning that sets 4-6 will be ignored. When cycling thru the presets in normal operation you will see only sets 1, 2 and 3 displayed. You can specify this by pushing and holding the presets button. A display will appear showing the 6 preset numbers from left to right, and a message will indicate how many are in use. By selecting, in this example, the number three with the corresponding radio button, you are specifying you want 3 sets of presets to be used. A line appears under that number. Pushing the presets button again selects and saves you choice, and now only sets 1 thru three will appear to be in use when scrolling thru them.
Somehow this was done on my radio by someone playing around, and only one preset was selected. When cycling thru them only one set then appeared. When I went thru the corrections process to say I wanted to use 6 sets, they all were 'returned' into service, and none of my stations I had set were lost.