I have encountered a weird instance in one of my user account.
In the mashup, under properties of the timeseries chart, I could not load or see the datafields.
However, when I change to my admin account or other user accounts, they are able to view the options under datafield1.
Even when I change the privilege of that account with issues to admin, it is still not working.
Yes. I have just check a few times and even set the privilege of the problem user to admin but it is still not working. Other users are working fine.
Sorry for the delay response as I am just back from a long vacation.
I don't see the related Mashup/Thing/data entities in the XML file you provided, it has a user entity only.
Try to see if there are any errors in the client browser. To do that, type F12 in Chrome or Firefox, refresh the page, go to "Console" tab and check the warnings/errors. If no any clues, please open a support ticket to check it via a remote session
If one of the previous responses allowed you to find a solution, please mark the appropriate one as the Accepted Solution for the benefit of others with the same issue.