tv360

I had the same problem and was able to resolve hooking into pum_popup_content and filtering out empty lines, comments, and empty p tags. Drop this into your functions.php or plugin:

/**
 * Fix for Popup Maker Gutenberg compatibility
 * Need to strip out comments, blank lines and empty paragraph tags
 */
add_filter( 'pum_popup_content', 'veer_popup_maker_gutenburg_compat' );

function veer_popup_maker_gutenburg_compat($content) {
	$content = preg_replace('!/\*.*?\*/!s', '', $content); // empty lines
	$content = preg_replace('/<!--(.|\s)*?-->/', '', $content); // block editor comments
	$content = preg_replace('/<p[^>]*><\\/p[^>]*>/', '', $content); // empty p tags
	return $content;
} 

Note that pum_popup_content only runs when a popup is saved/updated. So to see the change, you’ll need to click update since the popups are cached.

Hopefully this saves someone out there some time!