Likely is that the processes needed to launch qbitorrent have not yet loaded when qbittorrent tries to launch.
The simple fix is to use the sleep command in the Exec= line of the autostart file in ~/.config/autostart/ to delay the startup of the application by 20 or 30 seconds, allowing time for full initialization, first.
I tried that. But unfortunately it didn't seem do work. I tried delays of 10, 15, 20, and 30 secs. I tried running the command manually, "sleep 15;qbittorrent" and it ran successfully
In case any one stumbles on this later, the command "qbittorrent" works in Terminal, but not here for some reason. You have to use the full path: "/usr/bin/qbittorrent" to make it work