Zapier and Mailchimp

Does anyone have experience working with Zapier and Mailchimp? I have a zap that triggers with a new Patreon patron notification which sends an action of creating a new subscriber in first one MailChimp mail list and then a second MailChimp mail list (both mail lists in the same account).

Unfortunately, it’s somewhat inconsistent, Sometimes the new subscriber shows up just fine, but other times it doesn’t. Yet when I manually add the new subscriber, Mailchimp shows the source as Zapier, which makes me think it’s in there, but not showing up in the UI for some reason. Does anyone have any insight here? Thanks.

Shouldn’t you be able to check the subscriber lists by exporting them? That would narrow down any UI issues.