ID 354345 - Hiero cannot achieve realtime playback when monitor output is set to 2160p30

Problem summary
Cannot achieve realtime playback in Hiero 11 when monitor output is set to 2160p30. In Hiero 11 the sequence plays at approximately 12 frames per second, whereas in Nuke 10.5 it is capable of playing back in realtime.

This issue occurs with the Blackmagic DeckLink 4K Extreme capture card.

Steps to reproduce

1) Open Hiero.

2) Import an image sequence and drag it onto the Timeline.

3) Navigate to 'Window' > 'Monitor Output' to open the Monitor Output settings. Set the monitor output device to 'DeckLink 4K Extreme', the format to '2160p30' and the pixel format to 10 bit.

4) Play the sequence and notice that it plays at approximately 12 fps.


Reproduced by support
This bug has been reproduced in:
Hiero 11.1v4 - Windows 10 - CentOS 7 
Hiero 11.1v1 - Windows 10
Hiero 11.0v4 - Windows 10
Hiero 11.0v1 - Windows 10
Hiero 10.5v7 - Linux CentOS 7
Hiero 10.5v1 - Linux CentOS 7
Hiero 10.0v6 - Linux CentOS 7
Hiero 10.0v1 - Linux CentOS 7

Unable to reproduce bug in:
Hiero 10.5v7 - Windows 10

Earliest version tested
Hiero 10.5v7 - Windows 10
- This issue no longer appears in this version and has regressed.

Hiero 10.0v1 - Linux CentOS 7
- It appears that 2160p30 is not supported in Hiero 9.0v9 and earlier.

Expected behaviour
The sequence should play in realtime.

Actual behaviour
The sequence plays back at approximately 12 frames per second.