The second-tier support asked me to check the website on our server, I copied the website to our server and there seems to be no problem. You can login with the same info here:
The second tier support asked if you could create a copy of your website on your server, they can double check there as the issue can not be replicated on our server.
There is no guarantee but they are willing to take a look there. Please set the next reply as private and provide the website copy/staging on the server that has the issue so they can take a look.
On the staging, I was able to confirm that the load time for saving a product was 6 seconds when using only WooCommerce.
When using only WC, WPML, ST and WCML saving took 12-15 seconds.
After running WPML > Support > Troubleshooting > Synchronize post taxonomies for "Products" and "Variations" the load time was down to 6 seconds, when testing only with WC and WPML plus add-ons.
At this point zero impact by WPML after running the troubleshooting options.
So please follow the steps mentioned there and get back to us with the result.
Thanks for the screenshot. I did as you said. That solved the problem, but literally for two days. Now it's happening again and synchronization doesn't work anymore