Google Tag Manager is commonly used to add various features to a site. A script fragment is downloaded and placed in the head layout which inserts a standard script in each page.
This has items that you control through your Google Tag Manager account. It allows detailed recording of user actions on a page and can allow the addition of certain items such as a 'live chat' facility for example.

The problem however is that the standard Google Tag Manager script fragment doesn’t work properly on the home page of a Sellerdeck Desktop site. It is changed by the publish process, preventing the scripts from running. Effectively meaning that Google Tag Manager won’t work on the home page.

If for example, you are using it for adwords control, or for logging when items are clicked etc. then you will get no data for the home page and any item that you have added using the Google Tag Manager would not be shown on the home page.

The fix however is quite simple, with a slight modification to the script fragment.

Locate the text

and change it to

'gtm'+ '.'+'js'
Save the layout and upload the site.