ID 360932 - Toggle Gain and Wiping in Hiero doesn't work correctly

Problem summary
Toggle Gain and Wiping in Hiero doesn't work correctly

Customer reported version
11.0v2
Customer reported platform
n_a_windows

Steps to reproduce
1) Open Hiero
2) Import two bits of footage
3) Drag one to the viewer, and drop onto the A panel.
4) Drag the other onto the Viewer and drop onto the B panel
5) Increase the gain slider. 
Result: The left side of the wipe gets brighter as expected, the right side doesn't and gets darker.

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
11.2v2 - OSX 10.12.6 - Windows 10 - CentOS 7
11.1v5 - OSX 10.12.6 - Windows 10 - CentOS 7
11.1v1 - OSX 10.12.6 - Windows 10 - CentOS 7
11.0v4 - OSX 10.12.6 - Windows 10 - CentOS 7
11.0v1 - OSX 10.12.6 - Windows 10 - CentOS 7
10.5v7 - OSX 10.12.6 - Windows 10 - CentOS 7
10.5v1 - OSX 10.12.6 - Windows 10 - CentOS 7

Unable to reproduce bug in:
10.0v6 - OSX 10.12.6 - Windows 10 - CentOS 7

Earliest version tested
10.0v6 - This issue no longer appears in this version and has regressed.

Expected behaviour
Both inputs should adjust the same when toggling the Gain in the viewer

Actual behaviour
'A' panel adjusts correctly, 'B' panel gets darker.