Saving custom text on settings panel got a critical error

Hi, I’m testing the plugin on local but any time i want to save changes for Text Settings, the panel display a critical error.

https://drive.google.com/file/d/16ncPKxakOA2H1LIBcyzeYE8z-IUBlIQz/view?usp=sharing

This is the debug log:

[30-Mar-2021 21:11:13 UTC] PHP Fatal error:  Uncaught ValueError: Unknown format specifier "," in C:\xampp\htdocs\site\wp-content\plugins\my-calendar\my-calendar-settings.php:41
Stack trace:
#0 C:\xampp\htdocs\site\wp-content\plugins\my-calendar\my-calendar-settings.php(41): sprintf('March 30-%30, 2...', '<code>F j-%d, Y...')
#1 C:\xampp\htdocs\site\wp-content\plugins\my-calendar\my-calendar-settings.php(725): mc_settings_field('mc_multidate_fo...', 'Date Format for...', 'F j-%d, Y', 'March 30-%30, 2...')
#2 C:\xampp\htdocs\site\wp-includes\class-wp-hook.php(287): my_calendar_settings('')
#3 C:\xampp\htdocs\site\wp-includes\class-wp-hook.php(311): WP_Hook->apply_filters('', Array)
#4 C:\xampp\htdocs\site\wp-includes\plugin.php(484): WP_Hook->do_action(Array)
#5 C:\xampp\htdocs\site\wp-admin\admin.php(259): do_action('my-calendar_pag...')
#6 {main}
  thrown in C:\xampp\htdocs\site\wp-content\plugins\my-calendar\my-calendar-settings.php on line 41

What i want to do is change the default Event title (Grid) value to{time}-{endtime}, I’m testing this on a multisite (not sure if this could produce the error).

Does anyone have a similar issue?

Thanks in advance