ID 430178 - A render progress prompt appears when flipbooking with an OCIO config set while Nuke colorspace is active

Problem summary
A render progress prompt appears when flipbooking with an OCIO config set while Nuke colorspace is active.

Customer reported version
nuke.12.1v1

Customer reported platform
centos7

Steps to reproduce

1) In Nuke, press S in the Node Graph to open the Project Settings.

2) Select the Color tab and choose the Nuke colorspace.

3) Set the OCIO config to anything other than nuke-default.

4) Create a Read node with any footage and flipbook the viewer.

Expected behavior
The flipbook should display the flipbook window.

Actual behavior
The flipbook does not begin until the render prompt completes.

Workaround
Having the nuke-default OCIO config set allows the flipbook to continue without displaying a render window.

Reproduced by Support in

Nuke 12.1v1 - Windows 10

Nuke 12.0v1 - Windows 10

Nuke 11.0v1 - Windows 10

Nuke 10.0v1 - Windows 10

Unable to reproduce bug in:
Nuke 9.0v9 - Windows 10

Earliest version tested
Nuke 9.0v9 - This issue doesn't appear in this version and has regressed