A business user reported that the Add New Item link on the managed metadata term picker has disappeared. Easy one I thought, the term set needs to be set to Opened. I did just that, but the user still cannot see the Add New Item link.
It turns out the managed metadata column must also have its Allow ‘Fill-in’ choices setting set to true. This is pretty obvious when you read the help text of this setting: “Select whether users will be permitted to add values to the term set. (Only open term sets will allow ‘Fill-in’)“.
Note that this setting defaults to true when you pick an opened term set for the column. However, if you already have a closed term set linked to the column, and you re-configure the term set to be opened, then you must manually set the Allow ‘Fill-in’ choices setting of the column to true.