I have narrowed down the problem.
I tested website with Health & Troubleshooting plugin.
I entered troubleshooting mode with standard Wordpress theme active, and then one by one activating plugins. I activated Woocommerce and all Woocommerce addon plugins, I activated WPML and all WPLM addons.
This all worked perfectly. And editor was not blank, but showed new Gutenberg editor like you can see in this picture:
Then I activated X Pro Child Theme and editor was blank again, like you can see in this picture:
When I activate X Pro (not the child theme) editor also works perfect:
So the problem is the X Pro Child theme.
When performing this health check troubleshooting, no cache or optimization plugin was activated. Only Woocommerce and add-ons & WPML and add-ons.
Could you please look into this?
I already sent all credentials via secure note on first post.