ID 509221 - Player: On macOS, maximising the Flix Client and then entering Player fullscreen causes panels to look stretched

Problem summary
On macOS, entering fullscreen on the Flix Client window, then fullscreen on the Player results in panels being stretched vertically. This does not occur on Windows.
 
Customer reported version
Flix 6.3.6
 
Customer reported platform
10.14
 
Steps to reproduce
1) On macOS, go to a show that isn't 1.77 and open any sequence revision - the bug reproduces on all aspect ratios but it's more evident on aspect ratios like 2.35 or 2.39).

2) Make the Flix Client fullscreen.

3) Make the Flix Player fullscreen (last button on the right below the Player).
 
Expected behaviour
Panel maintains the same proportions it had before the Player fullscreen.
 
Actual behaviour
The panel appears stretched in fullscreen.

 
Workaround
Enter fullscreen on the Player when the Client isn't fullscreen.
 
Reproduced by support
This bug has been reproduced in:
6.4.0 - macOS 10.14.6 - macOS 11.6.2
6.3.6 - macOS 10.14.6 
6.2.2 - macOS 10.14.6
 
Earliest version tested
6.2.2 - This issue appears to be in all versions of the product