Note that the Mautic devs responded and provided a fix for my broadcast email issue:
https://github.com/mautic/mautic/issues/3660
Check these 2 directories:
- app/bundles/CoreBundle/Command/SendChannelBroadcastCommand.php
- app/bundles/ChannelBundle/Command/SendChannelBroadcastCommand.php
If you have both files remove app/bundles/CoreBundle/Command/SendChannelBroadcastCommand.php