I would expect Asio4all to work better on Win7, because Asio4all is ancient. It took a lot of trial and error and messing around to get it to work properly on Win10, but I got there.
Turning off my other USB interface was definitely key, just to stop the computer getting confused and trying to use it all the time. So I’d recommend turning off your Scarlett and probably the MIDI one.
And Win10 has a hidden audio device called Microsoft GS Wavetable Synth that seems to take control before Asio4all can, and prevents the S2400’s 10 inputs working. Not sure if Win7 had that, but go to View > Show hidden devices in Device Manager and have a look and disable it if present.
I could try installing a Win7 virtual machine and seeing if I can get Asio4all working, but I imagine getting the S2400 USB to pass through to the VM would be more of a hassle than Asio.