Hi There,
You can try adding this in your wp-config.php located at the root directory of your site.
define( 'WP_MEMORY_LIMIT', '256M' );
define( 'WP_MAX_MEMORY_LIMIT', '512M' );
You can add it before the line
/* That’s all, stop editing! Happy blogging. */
Hope that helps
If that does not work,
You could try testing for a plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
Thanks
Joao