I’ve now upgraded WordPress to 5.9.3 and Event post to 5.6.1 and now all works.
So i think that Event Post 5.6.1 is not completely compatible to WordPress 5.8.4.
It can’t access to colors array returned from WordPress wp_get_global_settings function.
The wp_get_global_settings is been introducted in 5.9 WordPress version … https://developer.ww.wp.xz.cn/reference/functions/wp_get_global_settings/
