Good afternoon. Today I faced the same problem. However, in my case, the problem was caused by a conflict with the Element or plugin of the latest version (3.3.0). When Elementor was deactivated, the import started working. In my case, “Enable jQuery Migrate Helper” did not solve the problem, because at one of the import stages, I could not edit the fields. Since the Elementar plugin is very common, you should pay attention to this error.
