In order to make sure that the admin panel is visible when you are in backend, make sure that the following criteria are met:

1. Make sure you are logged in to the BE of same domain.

In a multi-domain setup, if you are logged in www.domain-a.com, and you try to view www.domain-b, then don’t expect the preview / admin panel to work.
This simply does not work!

2. user and/or group setup:

admPanel=1
admPanel {
enable.edit = 1
enable.edit.hide=1
enable.preview = 1
enable.cache = 0
enable.info = 1
module.edit.forceDisplayFieldIcons = 1
module.edit.forceDisplayIcons = 1
module.edit.forceNoPopup = 0
hide = 0
}

3. root template setup:

config.admPanel=1

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