Unresponsive/unsupportive author(s) of the plugins
I purchased the plugin "Advanced Custom Fields for ClassiPress" via "appthemes" and I contacted with the developer "Mohsin" regarding some issues via email, as instructed in the support section.
But, I do not get a response. He is also the author of other plugin "Dynamic Multi- Level Fields". I did not get any response regarding the issues with that plugin, either. The Appthemes should have removed those plugins and the authors if the authors can no longer provide the support for their plugins.