You might be right, but I have sometimes switched to F mode early and it works fine every time. And sometimes I forget to switch until very late in the sequence, which prompts me with a message reminding me to switch to F mode, which also works every time. So I am not sure the switch sequence order or timing is significant or not.
When I read this message, I had a hard time coming up with an explanation for why the upload might be getting stalled like that. It always happens nearly instantaneously for me.
I wonder if the sync between Litchi Mission Hub and the phone/tablet could be part of the problem. If the mission is created on a desktop in the Mission Hub, then it obviously needs to sync with the control device, before the control device can upload the new mission to the bird. Since the WiFi link cannot be connected to both at the same time, there needs to another path for the sync to happen. Could the mobile data link (non wifi) be trying to complete the sync with mission hub while the bird is being uploaded? If the phone/tablet is in Airplane Mode when the Litchi app is opened, and the Wifi is connected solely to the bird, how does the sync work? Does it depend on the Litchi app being opened before the connection to the bird, while device is still connected to the internet, so the device can be synced with Mission Hub before the flight?
The app is obviously waiting on something to happen before it will upload the mission, and the only two things I know it needs are a switch to F-mode, and a valid mission plan in memory on the control device.