Latest update changes text color in full calendar

Love the plugin, which has worked beautifully for us for nearly 12 months until now.
My [fullcalendar] used to display the text of events in white letters against colored backgrounds that differed according to their assigned categories. With the latest updates of WP FullCalendar, the background colors are unchanged, but without any intervention on our part, the color of the text is now a dark blue, making it virtually unreadable.
How can I revert back to the white-colored text that we previously displayed?

https://www.ads-software.com/plugins/wp-fullcalendar/