Resolved in: 4.3.2
In WPML 4.3 we have introduced a new way of handling translations coming from plugins.
For that way to work, we need to scan them first.
However if you have the constant “ICL_DONT_LOAD_LANGUAGES_JS” defined, then the scan would not complete at this time as it stops loading some required scripts.
Our developers are working on releasing a fix soon.
For now, it is recommended, at least for the initial scanning to not set “ICL_DONT_LOAD_LANGUAGES_JS” constant