Multisite theme manager freezing when searching themes from subsite menu after WP 4.5 upgrade

Hi,

Using the Multisite Theme Manager v. 1.1.1. with Prosites 3.5.2 and just started to screen freeze when we use the search box filter, was all good until the WP 4.5 update yesterday. Happens to every site regardless of activated plugins.

Debug Log:
Undefined index: preview in....../wp-content/plugins/multisite-theme-manager/multisite-theme-manager-files/themes/3-eight/index.php on line 50

Line 50:
"><?php _e( 'Preview', 'wmd_multisitethememanager' ); ?>

Direction?