When you say, “other options do not seem to be saving either”, do you mean the standard WP settings? If yes, do they save correctly when EM is deactivated?
wp core settings are saving just fine, I was referring to other EM settings. I am reverting to 5.4 now to see if that version will work for the time being.
reverting to 5.4 did not fix change anything. also the submenu is doing this as well…http://www.tiikoni.com/tis/view/?id=19fed5b
Is everything working okay when you disable wp-facebook-open-graph-protocol ?
are you using WPML by any chance? If so, then you may need to increase your php max_input_vars argument – http://www.php.net/manual/en/info.configuration.php#ini.max-input-vars
as for the 500 error, if you can turn on debug mode or check your logs for the error, that may be helpful.
the screenshot you sent indicates other potential issues, related to user capabilities. I guess you need your settings page to work before you can try resaving 🙂