jerky framerate on mkv interlaced videos

[sappyyy]

Hello, just discovered your software, and already loving it, thank you!
However I've noticed some issue with .mkv interlaced files - the playback and framerate becomes jerky on cutted video. I've checked it on many files with MPC-BE and VLC - on my own captures and downloaded ones - all seems to have this problem.
And some media info is changed on cutted file from

 Scan type                                : Interlaced
 Scan type, store method                  : Separated fields
 Scan order                               : Top Field First

to

 Scan type                                : Interlaced
 Scan type, store method                  : Separated fields (2 fields per block)
 Scan order                               : Top Field First

Here's example -
https://drive.google.com/drive/folders/1AM04yQt66IoKWvUuE140NGkC4ElOMF9w?usp=sharing

[mifi]

Thanks for sharing. I just tried your file and even without cutting, just sending it straight through ffmpeg from the command line, it produces a jerky output:

ffmpeg -i Test\ Interlaced\ 01\ -\ Original\ Good.mkv -c copy out.mkv

ffmpeg also spews out a lot of warnings while processing:

[matroska @ 0x7f92057101c0] Invalid DTS: 119 PTS: 40 in output stream 0:0, replacing by guess  
[matroska @ 0x7f92057101c0] Non-monotonous DTS in output stream 0:0; previous: 119, current: 0; changing to 119. This may result in incorrect timestamps in the output file.
[matroska @ 0x7f92057101c0] Non-monotonous DTS in output stream 0:0; previous: 119, current: 40; changing to 119. This may result in incorrect timestamps in the output file.
[matroska @ 0x7f92057101c0] Non-monotonous DTS in output stream 0:0; previous: 119, current: 80; changing to 119. This may result in incorrect timestamps in the output file.
[matroska @ 0x7f92057101c0] Non-monotonous DTS in output stream 0:0; previous: 380, current: 320; changing to 380. This may result in incorrect timestamps in the output file.
[matroska @ 0x7f92057101c0] Non-monotonous DTS in output stream 0:0; previous: 380, current: 340; changing to 380. This may result in incorrect timestamps in the output file.
[matroska @ 0x7f92057101c0] Non-monotonous DTS in output stream 0:0; previous: 540, current: 480; changing to 540. This may result in incorrect timestamps in the output file.
[matroska @ 0x7f92057101c0] Non-monotonous DTS in output stream 0:0; previous: 540, current: 500; changing to 540. This may result in incorrect timestamps in the output file.

So I think it's a bug in ffmpeg. Not much I can do, although feel free to file an issue at ffmpeg.org