This thread is resolved. Here is a description of the problem and solution.
Problem:
The client was unable to generate .mo files for WPML String Translation even though the folder permissions were set to 755. The error suggested trying again via WPML->Theme and plugins localization. A discrepancy was found between the Site Address (URL) and the WordPress Address (URL), and the .htaccess file was not writable.
Solution:
We matched the Site Address (URL) and the WordPress Address (URL) temporarily and attempted to generate the .mo files again, which was successful. This confirmed that the issue was related to the URL mismatch. However, since this mismatch normally shouldn't cause problems, we reverted the settings back to their original state. Additionally, to resolve the .htaccess file issue, we recommend making the .htaccess file writable so that WordPress can update it as needed. This might resolve the problem entirely.
If this solution does not apply to your case, or if it seems outdated, we highly recommend checking related known issues at https://wpml.org/known-issues/, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If issues persist, please open a new support ticket at WPML support forum.
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