Error notice so i cannot adjust size width height of images

Hello there
Congratulations for your amazing effects -plugin.

i am using your plugin with avada theme

I get Notice: Undefined index: cap_thumbwidth in …public_html/wp-content/plugins/image-hover-effects/plugin.class.php on line 223

so i cant adjust size(width-height) of images.I use square effects.It only renders a 300 x 200 default size for all images.

i would like a kind of custom masonry layout.

thanks a lot
George