This seems like what’s happening to me. I’m on ACF PRO 5.2.0. Any time that I check a taxonomy term, the metabox disappears. If I check two terms quickly, it will disappear and then reappear. Check three terms quickly, disappear, reappear, disappear. I can see it’s cycling between display:hidden and display:block on the categorydiv box.
Figured it out by using admin_head and applying:
<style>
#adminmenu #toplevel_page_edit-post_type-acf div.wp-menu-image:before {
content: “\f116”;
}
</style>
Thanks!