That comma is very important . I encountered an issue where the commas were missing after "User Email"} :
{"field": "user_email", "label": "User Email"}\
this caused the Incident Review - Event Attributes to be hidden and the add new entry button to disappear as well. It was not until those changes were made that it all worked out.
{"field": "user_email", "label": "User Email"},\
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