Thanks Stefan for your test file.
In Cinelerra-GG, for what I are seeing, the problem is not cutting the
video in the Timeline; the video also freezes without cutting anything
and playing frome some points.

Your video use long GOP (max 250): there are I-frame, B-frame, P-frame.
The I-frames are at: I-0001, I-0220, I-0447, I-0697, I-0913, I-1163 and
I-1342.

Like me, you can do an easy test in Cinelerra-GG.
1. On the Timebar, in the Main Window, change the display from "Frames"
to "Hours:minutes:seconds: frames" (use Right Mouse Button on it, see
https://cinelerra-gg.org/download/CinelerraGG_Manual/Insertion_Point.html).
So you can see "Frames" instead of "Hours:minutes:seconds: frames".
2. Add two labels at 913 and 1163 (you can use "Go to" tool)
3. Move the Insertion Point at 930, for example, and press Play
(Numpad-3): it should work fine.
4. Move the Insertion Point at 850, for example, and press Play
(Numpad-3): video freezes until it reaches the I-frame (at 913).

The same happens for the other I-frames. It seems a problem around some
B-frame and P-frame. As Andrea_paz said, the MKV codec format can be
problematic if the encoding is not done well by the program (OBS?). I
don't use OBS Studio, so I can't try it using other output format codec.

Possible solutions:
a) As told by Andrea and Phyllis, using Transcode's Cinelerra-GG or an
other Convert tool.
b) In OBS Studio change the output codec, for example TS (Transport
Stream), MOV, MPEG2, or ???.

Because your video is yuvj444p h264 High 4:4:4 Predictive, in OBS can
you change any parameters of that? For example to yuvj420p and try?


IgorBeg

PS:
other Users have many problems with MKV files from OBS Studio using
Commercial NLE (LightWorks is one of them)
--
Cin mailing list
Cin@lists.cinelerra-gg.org
https://lists.cinelerra-gg.org/mailman/listinfo/cin