Ass Subtitles not rendering Malayalam Fonts

Ass Subtitle not rendering Malayalam fonts. it shows some square box instead of font. this is perfectly working in pc version. i tried from Fedora 30.

Expected behavior

show malayalam font correctly

Actual behavior

shows just boxes

Steps to reproduce

1. open the attached subtitle in any video longer than 25 minutes 02-Confrontation.ass
2. go to the 22:41 minute and see the issue

Screenshot / video

Context

App version

3.2.11

Android version

9.0

Device model

oneplus 5t

App mode

Smartphone

TV

Autos