ID 487657 - When flipbooking to HieroPlayer, with a custom OCIO config set via an environment variable, each flipbook will go into a different project, rather than the same one

Problem summary
When flipbooking to HieroPlayer, with a custom OCIO config set via an environment variable, each flipbook will go into a different project, rather than the same one.
This happens whether you set the environment variable locally, or at a system level.
This prevents users from comparing two flipbooked clips as they are in different projects.

Customer reported version
nuke.12.2v7

Customer reported platform
Linux

Steps to reproduce

1) Go to <NukeInstall>/plugins/OCIOConfigs/configs and copy the nuke-default directory to your temp directory.

2) Rename the copied nuke-default to testConfig

3) Open Terminal

4) Set the OCIO environment variable to the path of the config.ocio file in your testConfig directory, for example:

5) From the same Terminal, launch Nuke

6) In Edit>Project Settings...>Color, set the color management to OCIO

7) Read in any .exr sequence and view it

8) In the Viewer panel, Flipbook the Viewer

9) In the Flipbook dialog, set the Flipbook to Hiero Player and press OK. This will open HieroPlayer and start playing the Flipbook

10) In the Nuke session, again Flipbook the Viewer, with the same settings as previously. This will now create a second project inside HieroPlayer, rather than reusing the existing one

Expected behaviour
For all Flipbook's using the same color management system to be opened in the same HieroPlayer project:

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Actual behaviour
Each Flipbook creates a new HieroPlayer project

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Workaround
On Windows, use backwards slashes \ for your environment variable path, this seems to bypass the issue, however other OS's cannot use backwards slashes for paths.
Use config directories with the same names as the ones Nuke ships with, like nuke-default

Reproduced by support
This bug has been reproduced in:
Nuke/HieroPlayer 13.0v4 - Windows 10, CentOS 7.5, macOS 11
Nuke/HieroPlayer 12.1v1 - Windows 10, CentOS 7.5, macOS 11

Earliest version tested
Nuke/HieroPlayer 12.1v1 - This feature did not exist before this version