Are you connected to the controller with USB?
If so, I’m pretty sure I know what’s doing this, and why. A simple change that you can do on your end is this:
- Click ‘Devices’
- Double click your controller
- Click Next on the first page (Ruida)
- Change from ‘Serial/USB’ to ‘Packet/USB’
- Click Next until you get to the end
This is to do with the new temporary connection system, and is probably the underlying serial device system “holding” data, waiting for it to be a little bit full before it starts to send. The packet system works differently and doesn’t have that wait.
I’ll do a bunch of testing with larger files here and see if I can figure out why that delay is happening. How large (in kb) is the total size of the file you’re sending?