SOLVED: [EDIT] [10.11.1] update - No chapters anymore in movies/series episodes

[ClémentXVII]

[EDIT thanks to serlmercant, I realised that actually movies that were uploaded before 10.11.1 also lost their chapters]
Is anyone else unable to have chapters show up in their library since the 10.11.1 update? Any idea where I should look for more information?

Chapters were working great before the update.
All my files are extracted from the original discs using MakeMKV.
Chapters seem to have gone from the files uploaded before 10.11.1 
====
Before update 10.11.1: chapters available on all library

• Movies : chapters available and I could jump ahead or backwards
  
• Series episodes:
  

1. chapters available and I could jump ahead or backwards with a curved arrow pointing forwards/backwards
   
2. I could also skip to the next/ previous episodes with the ">|" or "|<" straight arrows
   

After update 10.11.1 (any client: Windows/Linux/Mac/Web/Android)
Chapters available on all library uploaded _AFTER_ the change to 10.11.1
No Chapters available at all on library items uploaded _BEFORE_ the change to 10.11.1

• Movies : chapters available and I can still jump ahead or backwards
  
• Series episodes:
  

1. chapters not available and I cannot jump ahead or backwards (no curved arrow pointing forwards/backwards in the interface, nor chapter lines in the timeline)
   
2. I can still skip to the next/ previous episodes with the ">|" or "|<" straight arrows