The blindscan plugin menu for TNAP 6 has changed a bit. There is now a multistream selection at the bottom. When multistream is set to off as shown, you will see transponders disappear at the end of the scan because they are MIS transponders.
129 West ku is a good, dependable place for MIS transponders. Shown next is the first stage of the scan completed and 14 transponders found.
But when the second stage of the scan completes, Only One transponder is shown. This happens because MIS is turned off in the blindscan plugin menu.
As another example, MIS was turned ON and the full range of the Universal ku lnb was allowed to scan which returned this:
Hopefully this clears up WHY transponders "mysteriously" disappear. It is all in the blindscan menu settings.
In the blindscan menu, look to the bottom right of the screen and you will see the blue button labeled as "Reset defaults". In a nutshell, all of the settings in the blindscan menu except for the satellite have been assigned defaults. This allows the user to customize the blindscan menu and have it saved after exiting from the blindscan menu. Therefore, use the Reset defaults feature as wanted or needed.
Also, the third entry from the top in the blindscan menu is: "Start Dish Motor". TNAP blindscan is set to not start the satellite dish motor until you tell it to or until the scan starts. The plugin is set up this way to avoid unwanted dish motor movement.