ID 390394 - Rendering comp containers, that have an alpha channel, to the Timeline makes the image appear partially transparent in the Sequence Viewer

Problem summary
Rendering comp containers, that have an alpha channel, to the Timeline makes the image appear partially transparent in the Sequence Viewer.

Customer reported version
Nuke 11.3v1

Customer reported platform
Ubuntu

Steps to reproduce

1) Open Nuke Studio and import an image sequence.

2) Drag the image sequence onto the Timeline and create a comp on it (right click > Effects > Create Comp).

3) Double click the comp container to open the comp. Inside the comp, you will need to create an alpha channel on your image (you can use a Roto node or a Keyer node, for example).

4) On the Write node, you will need to set the Channels dropdown menu to 'rgba'.

5) Save the comp and switch back to your Timeline.

6) Render the comp container (Right click > Render comp.

7) To see this issue, you can navigate to Edit > Preferences > Panels > Viewer (Sequence) and change the 'background' setting to 'checkerboard'.

Expected behaviour
The image should not be at all transparent in the Viewer.

Actual behaviour
The image appears partially transparent in the Viewer.

Reproduced by support

This bug has been reproduced in:
Nuke Studio 11.3v3 - Windows 10 - Linux CentOS 6 - macOS 10.13 (High Sierra)

Nuke Studio 11.3v1 - Windows 10

Nuke Studio 11.2v1 - Windows 10

Nuke Studio 11.1v1 - Windows 10

Nuke Studio 11.0v1 - Windows 10

Nuke Studio 10.5v1 - Windows 10

Nuke Studio 10.0v1 - Windows 10

Nuke Studio 9.0v1 - Windows 10 - Linux CentOS 6 - macOS 10.13 (High Sierra)

Earliest version tested
Nuke Studio 9.0v1
- This issue appears to be in all versions of the product