Internal SRT subtitles not recognized by Jellyfin

[kebbino]

Hi everyone, I'm experiencing an issue with Jellyfin:
I have multiplexed subtitle tracks into my MKV files using MKVToolNix:

• Italian track in SRT
  
• English track in SSA/ASS
  

On VLC, everything works perfectly: the Italian track plays automatically and is recognized correctly.
However, in Jellyfin, the subtitle button does not appear, and the Media Info shows no subtitle tracks at all—neither Italian nor English. I have already tried:

• Ensuring the Italian track language is set to ita in MKVToolNix
  
• Forcing a library scan in Jellyfin
  
• Testing the file on multiple clients
  

I’m attaching a screenshot from MKVToolNix showing both subtitle tracks for reference.
Does anyone have advice on how to make Jellyfin recognize internal SRT subtitle tracks reliably?
Thanks!