Hey Jessica,
I’m sorry you’ve been having these issues. There are a few different things that come to mind that could be to blame here, but the best first step in determining the culprit is to run through the complete set of troubleshooting steps here → https://theeventscalendar.com/knowledgebase/testing-for-conflicts/
If possible, try to create “sample”/testing orders after each step in that process, so that you can see if the Tickets email-sending is affected anywhere along the way.
It might sound tedious, but is actually a pretty quick process to go through and immeasurably valuable for troubleshooting.
Let us know what you find!
Thanks,
George