So if you have an Indiaman and move it onto the trade icon, it continues to exist (and flashes a coin?)

As I mentioned, my Indiaman-Fifth Rate-Sloop-Brig fleet moved onto one, got a flashing icon, but the Indiaman is gone. When I move the Fifth Rate, Sloop and Brig off the icon they stop flashing the coin, when I move them back they flash the coin again, in spite of the apparent loss of the Indiaman. This is just a glitch (or me being crazy?)