Also reached out to one of the plug-in developers, and he said it’s something in the theme’s jquery – well, he describes it better than me:
“I see the issue now.
So, the theme includes this CSS file: /wp-content/themes/evolve-plus/library/functions/css/theme-options.css?ver=4.1 Inside it uses classnames from jquery UI, but custom CSS rules: https://dl.dropboxusercontent.com/s/vzciyfjm7w51fp2/2015-01-26%20at%2017.59%202x.png?dl=0
Resume Manager, and the other plugins you found, and possibly more out there enqueue a standard version of the jquery UI css http://ajax.googleapis.com/ajax/libs/jqueryui/1.11.2/themes/smoothness/jquery-ui.css?ver=4.1
Because the CSS class names are the same, it applies the styles to the theme options.
Not sure what to suggest; I cannot de-enqueue the CSS in my plugin because the calendars won’t be styled. The them doesn’t include all jquery ui styles.”
Does this help?