Use one of these code snippets to fix a form view in popup. This example uses a button selector for the Elementor popup. Change a button selector to use this code with another popup plugin.

js_code_snippet.js

/**
 * A code snippet that triggers the "resize" once the popup is open.
 * Add this code to your custom JS file.
 */
jQuery( '.elementor-button[href^="#elementor-action"]' ).on( 'click', function () {
	setTimeout( function() {
		jQuery( window ).trigger( 'resize' );
	}, 100 );
} );

php_code_snippet.php

<?php

/**
 * A code snippet that triggers the "resize" once the popup is open.
 * Add this code to the file functions.php in the active theme directory.
 */
add_action( 'wp_footer', function () {
	?><script type="text/javascript">
		jQuery( '.elementor-button[href^="#elementor-action"]' ).on( 'click', function () {
			setTimeout( function() {
				jQuery( window ).trigger( 'resize' );
			}, 100 );
		} );
	</script><?php
} );

This gist is a part of the article Fix a form view in pop-up.

Documentation: https://docs.ultimatemember.com/
Support forum: https://wordpress.org/support/plugin/ultimate-member/