ID 408079 - GridWarpTracker gives incorrect results when using a SmartVector track and the Viewer is downrezzed.

​Problem summary
GridWarpTracker node gives incorrect results when using a SmartVector as a tracking source and the Viewer is downrezzed.

Customer reported version
nuke.n/a

Customer reported platform
windows windows7

Steps to reproduce

1) Open the attached script (or build a setup similar to below using moving footage)

​
2) Within the GridWarpTracker node, draw ​

​ a new Grid around an object and warp using the 'To' grid within the Viewer

3) Within the Viewer, track several frames of footage first with 'From', then 'To' selected
Result: Warp tracks correctly over the frame range using the SmartVector information, and the grid tracks to area

4) Downrez the Viewer to 1:2

5) Delete the keyframes on both the 'From' and 'To' values

6) Re-track both 'To' and 'From' now within 1:2 downrez active
Result: Warp does not track correctly over frame range, and the grid shifts from the area.

Expected behaviour
Track should work as expected when resolution is reduced using downrez option in Viewer

Actual behaviour
Downrezzing the Viewer when tracking causes the GripWarpTracker grid to slip when tracking

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
Nuke 12.0v1 - Windows 7 - MacOS 10.14.5 - CentOS 7 

Unable to reproduce bug in:
Nuke 11.3v5 - Windows 7 - MacOS 10.14.5 - CentOS 7

Earliest version tested
Nuke 12.0v1
- GridWarpTracker did not exist before Nuke 12 release