Strange I have the same problem with 5.7.10… Cannot click on a drop down list in the admin, got the “Cannot read property ‘id’ of undefined”
Maybe a conflict with another plugin or with new jquery… I’m on WordPress 5.0.3
Just to be more precise. It’s a Taxonomy subfield in a repeater. Empty is allowed. I return the term ID (not the object). Was working perfect before WordPress/Acf update…
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