Just in case someone else runs into this, I think I found the problem. While the sound pack provides a new ‘layout.json’ file, it does not work correctly. If you use it, the Seneca V does not even show up as an available plane.
So, after backing up the original ‘layout.json’ file (in case you need/want to go back), you must replace:
{
“path”: “SimObjects/Airplanes/Carenado_PA34_Seneca_V/sound/Carenado_PA34_Seneca_V.PC.pck”,
“size”: 36403086,
“date”: 133251140536530208
},
with all of the wave files included in the sound pack. Somehow, when I did this, I kept the above in the modified ‘layout.json’ file. While this still works to provide the new sounds, it leads to a problem when closing down MSFS. After deleting the above and saving it, MSFS started closing correctly.