I can confirm I'm seeing something similar. I'm running WP 5.1 and PHP 7.3 on a local Laravel Valet dev environment.
This is the error message I get on the speaker screen.
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<b>Notice</b>: Undefined index: fields in <b>/Users/Jay/code/metabox/wp-content/plugins/meta-box-aio/extensions/meta-box-group/class-rwmb-group-field.php</b> on line <b>338</b><br />
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<b>Warning</b>: Invalid argument supplied for foreach() in <b>/Users/Jay/code/metabox/wp-content/plugins/meta-box/inc/meta-box.php</b> on line <b>386</b><br />