ID 511961 - [S] To Avid: Clips in the automatically generated sequence cannot be extended from the start as they do not have the mark in set in the preferences

Problem summary
Clips in the automatically generated sequence published from Flix cannot be extended from the beginning, as they only have a handle at the end, ignoring the mark in that was set in the Flix preferences.
 
Customer reported version
Flix 6.4.0
 
Steps to reproduce
1) In Preferences > Third Party Apps > Avid Media Composer, make sure to have the following options set:

• Clip Duration - 480
• Use Flix Timing - Enabled
• Enable Mark In - Enabled
• Mark In - 120
• Enable Mark Out - Disabled

With these options I would expect there to be plenty of space to extend a clip from the front or from the back once it's in Avid.
 
2) Publish a short Flix sequence to Avid (1 panel is enough).
 
3) In Avid, try to make the clip in the automatically generated sequence longer, extending it from the beginning.
 
Expected behaviour
Clip can be extended from the beginning by a maximum of 120 frames.
 
Actual behaviour
Clip cannot be extended at all from the beginning, only from the end. In the bin, the clip metadata shows the correct mark in point, but in the sequence it's clearly having a mark in of 00:00:00.
 
Workaround
Clips brought into the Media Composer timeline from the bin will have the mark in which was set in the Flix preferences, and will be able to be extended from both its extremities. 
Camera move animation on the 3D Warp will not be present when dragging clips from the bin, so this workaround is only viable on stills.
 
Reproduced by support
This bug has been reproduced in:
6.4.0 - CentOS 7 Server - Windows 10 Client - macOS 11 Client
 
Unable to reproduce bug in:
6.3.7 - CentOS 7 Server - Windows 10 Client - macOS 11 Client
 
Earliest version tested
6.3.7 - This issue doesn't appear in this version and has regressed