FFMPEG does not load Font from ASS file

I'm trying to burn an ASS subtitle file onto a video using ffmpeg. This is the style part of the ASS file:

[Script Info]; Script generated by FFmpeg/Lavc60.3.100ScriptType: v4.00+PlayResX: 384PlayResY: 288ScaledBorderAndShadow: yesYCbCr Matrix: None[V4+ Styles]Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, EncodingStyle: Dialog,"Dast Nevis",24,&Hffffff,&Hffffff,&H0,&H0,0,0,0,0,100,100,0,0,1,2,0,2,10,10,20,1

Although the "Dast Nevis" font is available on the system under ~/Library/Fonts, ffmpeg doesn't find it. Here's the ffmpeg command I am using:

ffmpeg -i geler-1080p.mp4 -vf "ass=geler.ass" -ss 10 -t 10  test.mp4

Here's part of the output:

 Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))  Stream #0:1 -> #0:1 (aac (native) -> aac (native))Press [q] to stop, [?] for help[Parsed_ass_0 @ 0x7fd45730c680] libass API version: 0x1701000[Parsed_ass_0 @ 0x7fd45730c680] libass source: tarball: 0.17.1[Parsed_ass_0 @ 0x7fd45730c680] Shaper: FriBidi 1.0.12 (SIMPLE) HarfBuzz-ng 8.3.0 (COMPLEX)[Parsed_ass_0 @ 0x7fd45730c680] Using font provider coretext[Parsed_ass_0 @ 0x7fd45730c680] Added subtitle file: 'geler.ass' (2 styles, 64 events)[Parsed_ass_0 @ 0x7fd45730c680] fontselect: ("Dast Nevis", 400, 0) -> /System/Library/Fonts/Helvetica.ttc, -1, Helvetica[Parsed_ass_0 @ 0x7fd45730c680] Glyph 0x62E not found, selecting one more font for ("Dast Nevis", 400, 0)[Parsed_ass_0 @ 0x7fd45730c680] fontselect: ("Dast Nevis", 400, 0) -> /System/Library/Fonts/GeezaPro.ttc, -1, GeezaPro

Apparently the font is not found, but why?