When you use a plugin, it works alongside all your other plugins. If one plugin breaks or changes expected behavior, it affects other plugins too. The dilemma with plugin development is that, if one plugin breaks, it may actually be caused by another plugin.
1. Ensure that WP and plugins are up-to-date
Keep your plugins up-to-date. With the advent of 1-click updates, there’s no excuse not to. If you’re using an old plugin version and come across some bugs, the odds are that those bugs have been fixed in the latest version.
2. Temporarily disable all other plugins
Did that fix the issue? If yes, re-activate your other plugins, one at a time, until you are able to experience the issue again. Once you find the problematic plugin, notify both plugin authors of the finding.
3. Temporarily switch the theme
Once in a while, an issue stems from custom code within the active theme’s functions.php file. Try switching to the stock twentythirteen theme. If the issue disappears, you know where to look.
4. Check the browser console and turn on WP_DEBUG
WordPress also includes some lightweight PHP debugging. Within wp-config.php, set the ‘WP_DEBUG’ constant to true. This will display any PHP warnings that wouldn’t otherwise appear. As always, report all findings to the plugin developer.
define('WP_DEBUG', true); // if WP_DEBUG already exists, set it to true
5. Provide plenty of details
The more information you provide, the better. This includes steps to reproduce the issue, and bonus points for a screencast or screenshots. Providing version information (below) also allows us to test for compatibility issues.