I am root admin of the Qlik sense and I have all the other admin security rules. However, I cannot duplicate any apps in my work stream in hub while I am the owner of these apps.(an error occurred 'app' could not be duplicated).
Also, I have enough space on the Qlik sense server disk.
I have recently updated to version 'February 2019' and have not made any changes to any security rules.
Check if you can do it in the QMC. I suspect that the root admin role is mainly focussed on QMC functionality. I recently wanted to do something like you're describing and had to create a new rule that applies to the Hub as well.