Portal pages related to dashboard tabs are not automatically transferred in update
sets. You can add portal pages to update sets from the Dashboard
Properties page using the Unload Dashboard function,
which unloads the entire dashboard with all related tabs, including portal pages.
In the source instance, navigate to the location of the dashboard you want to
unload, for example,
Select the dashboard you want to unload to an update set.
Click the context menu icon () and select Dashboard
Properties to open the dashboard record.
Click the context menu icon () and select Unload
Only perform this step once the dashboard is ready to unload, meaning that all
the content is added to the tabs.
Move the update set to another instance using standard update set
functionality. For more information, see Retrieve an update