Strong Testimonials – Uncaught Error 2.40.1

Just tried to upgrade and got the error below – entire site was unavailable until I rolled back. Thoughts appreciated. Thanks, Jay

[Sun Feb 02 15:37:26.130170 2020] [php7:error] [pid 21170] [client 34.73.10.133:28450] PHP Fatal error: Uncaught Error: Call to undefined function wpmtst_get_custom_fields() in /nas/content/live/sbmedia1/wp-content/plugins/strong-testimonials-review-markup/includes/class-review-markup-counter.php:83\nStack trace:\n#0 /nas/content/live/sbmedia1/wp-content/plugins/strong-testimonials-review-markup/includes/class-review-markup-counter.php(62): Strong_Testimonials_Review_Markup_Counter->find_first_rating_field()\n#1 /nas/content/live/sbmedia1/wp-content/plugins/strong-testimonials-review-markup/includes/class-review-markup-counter.php(24): Strong_Testimonials_Review_Markup_Counter->set_factors()\n#2 /nas/content/live/sbmedia1/wp-content/plugins/strong-testimonials-review-markup/strong-testimonials-review-markup.php(78): Strong_Testimonials_Review_Markup_Counter->__construct()\n#3 /nas/content/live/sbmedia1/wp-content/plugins/strong-testimonials-review-markup/strong-testimonials-review-markup.php(415): Strong_Testimonials_Review_Markup->__construct()\n#4 /nas/content/live/sbmedia1/wp-includes/class-wp-hook.php(288): wpmts in /nas/content/live/sbmedia1/wp-content/plugins/strong-testimonials-review-markup/includes/class-review-markup-counter.php on line 83