Sorry, I am also getting an error log re: images/display.
(I posted this on another post but realized it's not for the responsive template post.)

Code:
[13-Jul-2021 18:31:39 Australia/Sydney] Request URI: /index.php?main_page=product_info&cPath=1&products_id=20, IP address: 101.#1  require(/home2//public_html/.com.au/includes/templates/responsive_classic/templates/tpl_modules_main_product_image.php) called at [/home2//public_html/.com.au/includes/templates/responsive_classic/templates/tpl_product_info_display.php:58]#2  require(/home2//public_html/.com.au/includes/templates/responsive_classic/templates/tpl_product_info_display.php) called at [/home2//public_html/.com.au/includes/modules/pages/product_info/main_template_vars.php:153]
#3  require(/home2//public_html/.com.au/includes/modules/pages/product_info/main_template_vars.php) called at [/home2//public_html/.com.au/includes/templates/responsive_classic/common/tpl_main_page.php:178]
#4  require(/home2//public_html/.com.au/includes/templates/responsive_classic/common/tpl_main_page.php) called at [/home2//public_html/.com.au/index.php:94]
--> PHP Warning: Use of undefined constant LARGE_IMAGE_WIDTH - assumed 'LARGE_IMAGE_WIDTH' (this will throw an Error in a future version of PHP) in /home2//public_html/.com.au/includes/templates/responsive_classic/templates/tpl_modules_main_product_image.php on line 24.

[13-Jul-2021 18:31:39 Australia/Sydney] Request URI: /index.php?main_page=product_info&cPath=1&products_id=20, IP address: 101.
#1  require(/home2//public_html/.com.au/includes/templates/responsive_classic/templates/tpl_modules_main_product_image.php) called at [/home2//public_html/.com.au/includes/templates/responsive_classic/templates/tpl_product_info_display.php:58]
#2  require(/home2//public_html/.com.au/includes/templates/responsive_classic/templates/tpl_product_info_display.php) called at [/home2//public_html/.com.au/includes/modules/pages/product_info/main_template_vars.php:153]
#3  require(/home2//public_html/.com.au/includes/modules/pages/product_info/main_template_vars.php) called at [/home2//public_html/.com.au/includes/templates/responsive_classic/common/tpl_main_page.php:178]
#4  require(/home2//public_html/.com.au/includes/templates/responsive_classic/common/tpl_main_page.php) called at [/home2//public_html/.com.au/index.php:94]
--> PHP Warning: Use of undefined constant LARGE_IMAGE_HEIGHT - assumed 'LARGE_IMAGE_HEIGHT' (this will throw an Error in a future version of PHP) in /home2//public_html/.com.au/includes/templates/responsive_classic/templates/tpl_modules_main_product_image.php on line 24.