Hi Jill,
Thanks so much for reaching out!
Does this occur with all of your customers, or just with one particular customer?
If you do a test order and go to the WooCommerce order associated with the ticket, go to Order Actions and resend ticket email, do you receive the email?
If not, please follow our Testing for Conflicts Guide (basically switch to Twenty Seventeen theme and deactivate all plugins and custom code other than Modern Tribe plugins) and see if that helps narrow down the cause of this.
Note that https://wordpress.org/plugins/plugin-detective/ may prove helpful as well. (third-party, not guaranteed or supported by us)
Let me know how that goes!
Thanks,
Jaime