[Gelöst] Products variations disappear when I activate wpml

Background of the issue:
When I activate WPML plugins, product variations I've added (while WPML plugins were deactivated) just disappear in the backoffice.

Symptoms:
The variation doesn't show as soon as I activate the plugin.

Questions:
Why do some product variations disappear in the backoffice when I activate WPML?
How can I ensure that product variations remain visible in the backoffice after activating WPML?