Fatal error: Uncaught Error: Method name must be a string

Unable to add or edit booking objects. Getting the following error message in the Taxonomies and Other fields section.

Fatal error: Uncaught Error: Method name must be a string in /home/customer/www/mydomain.com/public_html/wp-content/plugins/ba-book-everything/includes/plugins/cmb2/includes/CMB2_Types.php:101 Stack trace: #0 /home/customer/www/mydomain.com/public_html/wp-content/plugins/ba-book-everything/includes/plugins/cmb2/includes/CMB2_Types.php(90): CMB2_Types->_render() #1 /home/customer/www/mydomain.com/public_html/wp-content/plugins/ba-book-everything/includes/plugins/cmb2/includes/CMB2_Field.php(929): CMB2_Types->render() #2 /home/customer/www/mydomain.com/public_html/wp-content/plugins/ba-book-everything/includes/plugins/cmb2/includes/CMB2_Base.php(315): CMB2_Field->render_field_callback(Array, Object(CMB2_Field), NULL) #3 /home/customer/www/mydomain.com/public_html/wp-content/plugins/ba-book-everything/includes/plugins/cmb2/includes/CMB2_Base.php(273): CMB2_Base->do_callback(Array) #4 /home/customer/www/mydomain.com/public_html/wp-content/plugins/ba-book-everything/includes/plugins/cmb2/includes/ in /home/customer/www/mydomain.com/public_html/wp-content/plugins/ba-book-everything/includes/plugins/cmb2/includes/CMB2_Types.php on line 101
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