Thanks for the clarification. By default, feature images are actually not meant to appear on the calendar – only in the pop-up on rollover (cf our demo website: https://wpshindig.com/events/).
If that is not the behavior you would expect, please suggest this feature in our UserVoice: https://www.google.fr/search?q=uservoice+events+calendar&oq=uservoice+events+calendar&aqs=chrome..69i57.4026j0j9&sourceid=chrome&ie=UTF-8 (the more votes, the more likely the feature becomes part of a future release).
Our extensions are small, lightweight WordPress plugins that add new capabilities to our core plugins. We hope you find them useful, but please note that they are optional extras which we do not support to the same degree as our mainstream products.
In this case, the “Display the Event Featured Image in Month View” extension was created almost 2 years ago and it’s possible it doesn’t work properly anymore. So if you wish to display the feature image in your Month view, I would recommend you to customize our plugin, following the instructions and the resources you can find here: https://theeventscalendar.com/customizations/
Hey there! This thread has been pretty quiet for the last three weeks, so we’re going to go ahead and close it to avoid confusion with other topics. If you’re still looking for help with this, please do open a new thread, reference this one and we’d be more than happy to continue the conversation over there.