This trigger requires that a thread from a new email address be attached to the box. Here is how you attach a thread to an email:
Streak limits creating boxes with to less than 2048 characters. A workaround is to use the formatter to truncate data sent to create the box to less than 2048 characters.
This usually means you've deleted a field from your pipeline, so the field key is invalid. To fix, reselect the pipeline on the action, it should update the custom fields to the ones that are available.
This trigger will fire every single time a field is updated in a box. So, if you update 4 fields in a box, the updated box trigger will result in 4 tasks. If you want it to only trigger once, you'll need to add a filter and an Edit Box step to your zap. One example of this would be as follows. Start with a filter that looks for the Notes field not containing "Triggered to Zapier:"
Then follow it by a action that updates the box like this:
That way, the first field that is updated will trigger and pass the filter, then update the Notes field. The subsequent fields won't pass the filter. These fields are just an example, you can use any field you want for the Filter and Edit Box actions.
An email address cannot be used as a filter on more than one box. When you see this error, that usually means the email address was already in use as a filter on another box.