This thread is resolved. Here is a description of the problem and solution.
Problem: I'm having a compatibility problem with Thrive Leads. The problem occurs like this: when I open a new form the loading screen of Thrive Architect (form builder) gets stuck, it loads endlessly.
Solution: The Thrive Architect plugin is not marked as being compatible with WPML (https://wpml.org/documentation/plugins-compatibility/) so there might be some issues between those two. In order to create a new form, you can temporary deactivate WPML. Editing the form works well so this will be needed only when creating a new form.
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