help with custom shortcode that stopped working

WordPress 4.2.3 made some changes to the way shortcodes work in order to fix a security issue. See here: https://make.wordpress.org/core/2015/07/23/changes-to-the-shortcode-api/

This is most likely the cause of your problem. See the Shortcodes with Bad Quotes section, and the accompanying workaround suggestion.

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