If you're not seeing your Tag listed, search for the tag name in the field and click the "Load More" option.
Tags are loaded from Keap Max Classic 30 at a time so if you have a large number of tags in your account it might require more than one click in order for it to show up.
The "Opt-In" field present in the Create/Update Contact action only works when the contact is first created. At this time, it is not possible to update a contact's opt-in/marketable status through Zapier. More information on Infusionft's documentation.
The accepted format for country codes is ISO 3166 alpha 3 codes - it uses three characters. So USA needs to be entered instead of US, for example. See more information here.
If your contacts aren't being marked as marketable, you likely need to flip the email opt-in field to "yes" in your action.
Keap Max Classic's "Send Email" action supports HTML messages. You'll choose whether you want HTML or plain text when configuring your action.
The Tag Added to Contact trigger may not behave as expected in certain cases:
Your Zap will only trigger if it's never seen the tag on the contact. One workaround is to turn the Zap off, remove the tag, turn the Zap on, and then re-add the tag.
If your Zap is watching for several tags, the Zap will only trigger the first time that any of those tags is added.
A Zap is watching for tags Zapier-1 and Zapier-2. A contact is tagged with Zapier-1 and triggers the Zap. If the same contact is then tagged with Zapier-2 a week later it won't trigger the Zap.
There are 500+ contacts with the tag in your Keap Max Classic account and/or the Zap errors with the following message:
READ ReadTimeout DNSHTTPSConnectionPool(host='api.infusionsoft.com', port=443): Read timed out. (read timeout=39)
To get around this, you can use a temporary tag to trigger your Zap. Create a tag that is only used for the purpose of triggering the Zap, such as Zapier. Then, you can add an extra step at the end of your Zap that uses the "Create/Update Contact" Action to remove this temporary tag. The goal is to keep the number of contacts with this tag as low as possible.
Unfortunately, a Zap can only trigger on 300 tagged contacts at a time. Try tagging fewer contacts and see if that helps.
If you've got more than one tag of the same name, your Zap will have trouble triggering. To fix this, clean up your tags in Infusionsoft, and then try reselecting the tag in the trigger setup.