When an .ass file contains large embedded fonts, Aegisub crashes

I tried adding two .ttf fonts, each about 20MB in size, into an .ass file and then loading it with Aegisub 3.4.2. Aegisub freezes and remains unresponsive even after 5 minutes, unable to start. However, if I subset the fonts and create smaller .ttf files before adding them to the .ass file, it opens normally.
Is there any way to open an .ass file with the full embedded fonts?