If there’s a problem with max_input_vars, this will tell you about it so that you can fix it. The only solution for max_input_vars issues it to alter the php setting. Doing this will be different depending on your hosting. For all I know, some hosing providers do not allow it to be changed.
If the issue is not max_input_vars and you don’t get a warning from this plugin then you can stop looking into solutions for this problem and look for something else, although given what you’ve said I don’t really know what else it could be.
