Finder Tabs drag and drop problem

Hi there,

I am using Mac OS Sierra 10.12.6 on Macbook Pro. If I have two finder tabs open and I try to drag a file from one tab to the other, I hover the file over the second tab, however the tab doesn't highlight to show that it has been selected, and if I continue to hold the file over the tab it won't spring open either.

I have searched the Finder preferences and the system preferences for a setting that might control this action, but can't seem to come across one.

Would anyone have any ideas how to get this to work.

Cheers, Colin