For which device or appliance are you trying to change it? My experience with ISR1100 has been that you need to run the request sdwan configuration reset option and start over. Reconfiguring the system IP has been impossible on that platform without starting over (versions 16.10.x and 16.12.1,16.12.3).
Thanks this helped me. I was trying "request platform software sdwan software reset". The actual command is "request platform software sdwan config reset". It told me the bootstrap wasn't saved and said it may lose connection with the controller, which I didn't want to take a chance of and start from scratch, so I gambled and saved it to bootflash with "request platform software sdwan bootstrap-config save". Once I ran the reset and reload, all the settings were still there, but I was able to change the system IP.
