Notes:
YTSubConverter 1.6.0
MPC-HC 1.9.19.21
LAV 0.76.0.7-git
XySubFilter 3.2.0.806 (git)
madVR 0.92.17
Other subtitle filter can't load the ass either
This same issue was previously reported under #56. It was already fixed, but I hadn't published a new release yet. You can now get version 1.6.1 which has the fix included.
I noticed more recent YouTube srv3 subtitle breaks YTSubConverter output ssa files
An example is with this video https://www.youtube.com/watch?v=MxwV963ZNEU
Script that I used:
Here's what I got with XySubFilter A wrong line of subtitle does appear on the beginning, but after that, none appeared at all.
Both ass and srv3 files is included in here https://gist.github.com/bagusnl/5a80264c19a07b1d2b06491944efd7f3
Notes: YTSubConverter 1.6.0 MPC-HC 1.9.19.21 LAV 0.76.0.7-git XySubFilter 3.2.0.806 (git) madVR 0.92.17 Other subtitle filter can't load the ass either