empty Event object when calling em_get_event() since version 5.9.9

Hi,

since the update to version 5.9.9, I always get an empty Event object without start and end dates etc (or the default ‘1970’) when using the em_get_event() function. If I change it back to 5.9.8.1 everything works as expected.

I use wpackagist to download the plugin via composer and use it as mu-plugin.
My WordPress version is 5.6.2, I use the roots/bedrock boilerplate and use roots/sage (version 10) as theme.
It does not only happen in the sage theme but also in wp default themes like twentytwenty. If i dump out the events object or use xdebug to debug the object, i see that the event object is more or less uninitialized.

I assume there might be a upgrade related issues, maybe there has been a database change or so and the needed upgrade script will not be executed when using the mu-plugin or similar, but I couldn’t figure it out by myself.

Thanks for checking this in advance.

best wishes