I can duplicated what @ronan ducluzeau (zeauro) and @Amir Shehata (ashehata) reported using 2.83 alpha.

No activity for more than a week. As per the tracker policy we assume the issue is gone and can be closed.

This seems like an improvement of existing code. Will set it to todo as it hasn't seen activity in the past 3 months

Is this problem still seen in the latest daily build?
https://builder.blender.org/download/

I guess this may be considered confirmed since efforts are made to fix the issue.

I don't know if I got it wrong, but even testing on the informed version, I can't reproduce the problem.
Keyframes are generated.

This patch has been committed, but still the known issue needs to be added. I will do that later today when I am in office.

I would expect that when selecting a marker in this case would select the camera where the marker belongs to and select the marker that is under the mouse button. But this is an assumption and would like the tracking module to see what actually needs to happen.

Hi, thanks for your patch.

Closing this for a couple reasons:

The viewport and the movie clip editor should display the selection of the markers in the same way. Fixing the crash shows that the selection drawing isn't handled the same.

In my previous diff I unintentionally changed the false parameter to true. This diff changes it back to the original setting.

Can confirm.
Looks like both issues need to be solved [importing image sequences as well as the crash for negative frames...]

"I don't think use of such strong imperative statement is something what belongs to a manual."
Thanks for being so diplomatic. In my defense I was recovering from a visit to the dentist.

Having the mention of time codes is fine, but i am not happy with the current placement of the information and its wording:

• Such information does not belong to an Introduction section, but more like Best Practices or so.
• I wouldn't recommend converting video file to an image sequence this has implications down the road. Rather, build timecode.
• I don't think use of such strong imperative statement is something what belongs to a manual.

@Dalai Felinto (dfelinto). I think this is fine. I now have a workaround, as you wrote. Thanks for looking into it.

Edit: old file is used (09/2016), not a file saved in blender 2.80 or 2.81

So I dig a bit further with blender-2.81 0547a7753643:
Edit: old file is used (09/2016), not a file saved in blender 2.80 or 2.81

Thanks but we can't use private files in your debugging process. Another round of questions:

I tested it again with blender-2.81 0547a7753643 but still the same issues with older Blender file.
I have attached a video where you can see the behaviour. And in the same video there is a test with the same video file, but with a new Blender 2.81 file from scratch. Here are no problems and the prefetch works as intended.

@Michael P. (forest-house) Can you test with the official 2.80 release (blender.org/download) and also a night build (builder.blender.org) to see if the problem persists?