Infinite Wordpress and Upfront conflict

Hi there. This WPMU Dev account belongs to my client, who built three sites using the Upfront theme 'Fixer'. After updating Upfront recently, I now can't ping these sites for updates via my Infinite Wordpress management software - I get connection errors. I can still use IWP to access wp-admin, though. Here's the error message below.

It looks very much like Upfront sees a conflict with IWP. IWP directed me to contact you.
PHP Fatal error occurred: Uncaught Error: Call to undefined function get_current_screen() in /home/website/public_html/wp-content/themes/upfront/library/class_upfront_compat.php:93 Stack trace: #0 /home/website/public_html/wp-includes/plugin.php(235): Upfront_Compat->prevent_conflicted_children_updates(Object(stdClass))

#1 /home/website/public_html/wp-content/plugins/iwp-client/helper.class.php(210): apply_filters('site_transient_...', Object(stdClass))

#2 /home/website/public_html/wp-content/plugins/iwp-client/installer.class.php(805): IWP_MMB_Helper->iwp_mmb_get_transient('update_themes')

#3 /home/website/public_html/wp-content/plugins/iwp-client/stats.class.php(276): IWP_MMB_Installer->get_upgradable_themes(Array)

#4 /home/website/public_html/wp-content/plugins/iwp-client/helper.class.php(125): IWP_MMB_Stats->get_updates(Array, Array)

#5 /home/website/public_html/wp-content/plugins/iwp-client/stats.class.php(467): IWP_MMB_Helper->iwp_mmb_parse_action_params('get', Array, Object(IWP_MMB_Stats))

#6 /home/website in /home/website/public_html/wp-content/themes/upfront/library/class_upfront_compat.php on line 93.

Thanks for any help you can offer.