I'm running into an issue where Magento 2.3.4 is not sending the shipment confirmation email after I enter the shipment for an order.
I have tried to send the shipping details (by checking the box to send customer notification) and it does not send.
If I go into the Admin page, go to Sales > Orders, pull up the shipment, and then click "Send Tracking Information", the email is also does not send.
When I press "Send Tracking Information" it asks me for confirmation "Do you really want to send the customer an e-mail of the order" and then the screen remains blank with a text "Sent by Shipment Number".
Debug.log & cron.log
main.INFO: Cron Job sales_send_order_shipment_emails is run   main.INFO: Cron Job sales_send_order_shipment_emails is successfully finished
When I place an order, the order confirmation email is sent correctly.
When I invoice the order, the invoice email is sent correctly.
Why are the shipment emails not being sent when a shipment is entered?