Editing .ass subtitle will no longer show them after muxing - MKV container

[Messerschmitt]

I'm using Subtitle Workshop as I wanted to modify the subtitles found in a .mkv container. After extracting them from the .mkv and using Subtitle Workshop to take out a line, and muxing them with mkvmerge, the subtitles no longer show up.

After trying to mux the .ass subtitle without modifying it using Subtitle Workshop, subtitles show up after muxing. But as soon as I modify it (take out a line), save it, and mux it, subtitles no longer show when watching the movie.

Why would that be? Anyone could please help me out?
How do I properly modify the subtitles?
Thanks

[Baldrick]

Are you exporting as an ass? or srt?

You could try edit the ass subs aegisub instead.

[Ai Haibara]

Are you sure you're using the latest versions of mkvtoolnix (for mkvmerge, as well as mkvextract), and whatever you're using to extract from MKVs?

I'll second what Baldrick said about using Aegisub over Subtitle Workshop to edit .ass-format subtitles. Aegisub's more likely to support the format better than Subtitle Workshop.

[Messerschmitt]

Thank you, using Aegisub worked.

Quick unrelated question. Any reason why when using mkvmerge, even just re-muxing the original .ass file extracted (non edited), changes the .mkv movie file size compared to the original .mkv? If no subtitle changes (lines added/removed/edited) are made, wouldn't it be normal for the size to remain the same?

[poisondeathray]

Quick unrelated question. Any reason why when using mkvmerge, even just re-muxing the original .ass file extracted (non edited), changes the .mkv movie file size compared to the original .mkv? If no subtitle changes (lines added/removed/edited) are made, wouldn't it be normal for the size to remain the same?

What was difference in size, like a few kb ? That can be normal

There might be differences in the mkvmerge version, or one might use header removal compression and the other one not

If it's something huge, then something else is up

[Messerschmitt]

Yes thats correct, it's only a few kb difference.

Where are some options like header removal to go and check?

[poisondeathray]

mediainfo will show "muxing mode: header stripping" for audio and video when viewed in text mode (view=>text)

in mkvmerge builds (v4.0+) header stripping was added and enabled by default. Prior to this it wasn't an option. You can disable in the options (many people do because it can cause playback problems with devices) . To disable it, checkmark "disable header removal compression by default for audio & video"

The difference might be a few kb, so it usually not worth it IMO.

I just took a small test sample 99.9MB disabled. 99.8MB enabled.

[Messerschmitt]

Thanks poison.
mediainfo was very interesting. I found out the files were made with mkvmerge v3.4.0, so I installed the same version as well. However, using the subtitles extracted with MKVExtractGUI2, not modified, it still gives me a difference of 2 bytes when using mkvmerge v3.4.0 (much more closer than v5.7.0 did).
Do you think that is because when extracting with MKVExtractGUI2 latest version, it might change the size of subtitles? Would a different version of MKVExtractGUI2 be different?

P.S. I will be out of town for 2 weeks, but I will look forward to hear any help when I come back

Cheers