So if you have an autoexec in cfg in the custom folder, it will likely override mastercomfig. So that's why that isn't working.
I'd recommend referring to the installation instructions: https://docs.mastercomfig.com/en/latest/setup/install/#custom-configs.
i.e., you need to create a user folder in cfg and then move your own autoexec in there.
Also, I would recommend using the mastercomfig transparent viewmodels and null cancelling movement addons instead of the autoexec settings.