Hello,
Sorry but unfortunately we couldn’t reproduce that issue here. In our tests with feature-headers-logged.html + header transparent the dropdown opens normally. Maybe you have another change in the HTML ? Anyway, the best way on this case is send us the entire HTML code you are trying for the <header>. You can use a service like https://pastebin.com to generate a link with your code and share with us.
Would be great and even better you send a online test link with your website for us, so we can inspect your code and discover where is the issue.
Kind Regards,
Rodrigo.
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