I do not see this error. But the issue could be related to ACF 5.7.8 update and not WP 5.0.
According to the Changelog:
https://www.advancedcustomfields.com/blog/acf-5-7-8-release/
* Fix – Fixed all metaboxes appearing when editing a post in WP 5.0.
Wondering if this could be related. As soon as I’ve got time I will try to reproduce the issue between 5.7.7 and 5.7.8.
