Zendesk uses a unique method to sort tickets. As a result, if you're using the "Recent Ticket" trigger, only tickets that find their way into the "Recent Tickets" view in Zendesk will trigger your zap. This can be confusing because the behavior that gets tickets into that view can be different than expected.
The easiest solution is to create a custom view for whatever tickets you want to have trigger your zap, then use the "View Ticket" trigger to get that zap to trigger. This eliminates the ambiguity of Zendesk determining what is "recent".
We don't currently support HTML for this field, but it is a feature request. Unfortunately, right now, there is no way to format the comment with bold, italics, etc. You can add line breaks by hitting enter to put them on different lines, but multiple line breaks will be reduced to a single line break. That means that this:
Will result in this (note only a single line space between the lines):
If your Zap is trying to fill a required field of a new ticket using only fields from the trigger, sometimes you will see errors because the fields you chose from the trigger didn't contain any data. For example, say you map the body of an email to the first comment on the ticket. If an email without a body comes through, Zendesk will prevent Zapier from making the ticket.
An easy fix is to add some static text along with the trigger fields. For exampling, adding "Orig Email: " as a prefix for the first comment will ensure that field is never empty.
Failed attempts to connect your Zendesk account to Zapier are usually because the account being connected isn't an admin account inside of Zendesk. You'll need to make sure you're connecting using a Zendesk user who is also an administrator for this to work.
It is also possible you have API access disabled inside Zendesk. To turn it on, go to your API Channel Settings (Channels > API) and enable the API.