In your calendar dashboard under Events > Import Feeds > Import Feeds tab >
You click on the Refresh button, but the feed never gives you a confirmation message that the sync/refresh operation completed.
Most likely, the reason could be that your host is reaching it's PHP memory limit -- and then the feed hangs.
I suggest increasing the memory limit, and try the feed refresh again -- it should finish, then produce either a confirmation or an error message -- this is how you know it finishes.
There are 4 ways to increase your PHP memory limit:
Add this to your wp-config file:
Edit your PHP.ini file (requires access to your server files). If you have access to your PHP.ini file, change the line in PHP.ini
If your line shows 64M, try 256M:
memory_limit = 256M
Edit your . htaccess file. If you don’t have access to PHP.ini try adding this to an . htaccess file:
php_value memory_limit 256M
Contact your Web Hosting Support
Ask your web host to increase the upload_max_filesize value for you to 256M