Recently theme makers and users have had some trouble with the tumblr controls, and it looks like tumblr have changed the code - or are currently in the process of doing so.
This is why the tumblr controls work for some and not for others.
If your tumblr controls do not work correctly
Tumblr have changed the name of the class and deleted the id on the new code.
So instead of coding with the id:
You need to change it to:
.tmblr-iframe.tmblr-iframe--desktop-loggedin-controls.iframe-controls--desktop
Or change it to one of the classes:
.tmblr-iframe
.tmblr-iframe--desktop-loggedin-controls (css visible if logged in)
.iframe-controls--desktop
If your tumblr controls still does not show, it might be because it’s hiding behind another div. Add this to the tumblr controls css:
z-index:999999999!important;