This thread is resolved. Here is a description of the problem and solution.
Problem:
You are trying to use different domains per language on your WordPress site with WPML. Despite correct server configuration and active SSL certificates on both domains, WPML reports that the domain is invalid.
Solution:
We recommend disabling the "Validate on save" option, entering your second domain, saving the changes, and then testing if the domain works. Sometimes the validation message can be a false positive. After translating the page, check if you can reach it via your secondary domain. If this doesn't work, your second domain may not be configured correctly. For more information, please visit this link.
If this solution is outdated or does not apply to your problem, we recommend opening a new support ticket. We also recommend checking the known issues page (https://wpml.org/known-issues/), verifying the version of the permanent solution, and confirming that you have the latest versions of themes and plugins installed.
This is the technical support forum for WPML - the multilingual WordPress plugin.
Everyone can read, but only WPML clients can post here. WPML team is replying on the forum 6 days per week, 22 hours per day.