Please enable SQL level logging, delete any existing logfile, and then login and reproduce the issue, ensuring you click on each of the tabs when a table is selected. Then, send over the logfile.
See attached file.
Just drag a tab near an edge of a panel, and when it lights up blue to indicate when the tab will dock, let go of the tab.
Some parts of the screen highlight in blue but when I release the button the tab goes away and nothing happens. Most peculiar.