Hi @officezen,
Here are some solutions that might work, in no particular order, please try each one and let me know if/which one solves your problem:
– This could be a result of a plugin or theme conflict.. Please try a different theme temporarily such as Twenty Seventeen, or, disable all plugins and then check if the problem recurrs — then re-enable each one until you find which one caused the problem.
– Make sure that your Calendar page is set to the right page in the settings (no need to use shortcode on a page set as the default in the plugin settings)
– Try turning on/off “Strict compatibility content filtering” in Events -> Settings –> Viewing Events.
– Try turning on/off “Use frontend rendering” in Events -> Settings –> Advanced
Resetting permalink settings to Plain and back to my custom style fixed the issue (thanks to the tip from Ben).