I was recently informed that you can only put one value in a Custom Variable field of a segment. Honestly, I'm surprised this hasn't been an issue before that has led to a change in this feature. If I'm trying to create a segment targeting a particular list of clients, it would be extremely inefficient to have to put each client ID in a separate Custom Variable field. I would recommend creating a way to add multiple values in the field to be used as an "OR" function within the list.
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