All 3 flight modes work for me (at least on the planes I use - Apprentice, Cessna 150, Timber Evolution, Carbon Cub). I'm using my DM TX16s MK2 (EDGE Tx) with the USB game controller and setup ch8 for the flight modes with 3 pos switch SE to select modes. Do the usual setup of inputs, mixes, outputs. I also add voice so I know the mode I select. I do have 8 channels working properly.
Then I calibrate my controller in RF to verify the switch works properly. Finally I edit the airplane radio to match the channel (8) for mode and then select the appropriate name for each switch position.
I am not using the 'software controller', the documentation provided doesn't seem to work for me and I want to 'fly'. Don't want to spend any more time trying to figure it out. Maybe it's because I don't use a spek controller.
I should also mention I've only been in the RC hobby for 3 months and the learning curve has been very steep. I'm not as mentally agile as I use to be. Someday I hope to fly an actual RC plane but for now I need a lot more sim practice.