Well, after a few more days of tests I think it's time for me to move this issue onto a VB forum.
My TX/RX camera footage doesn't really prove anything. If VB closes the port and the Arduino sends serial data, TX WILL NOT FLASH. VB continues to randomly close the port, say the device connected is not functioning, or just tell me outright that the port doesn't even exist (even though the device manager may show everything's working fine).
Ciao for now...