MAME snap missing BGFX effects?

I installed the MAME snap, and when I configure the Video Mode to be BGFX, MAME immediately exits with the following below. I can verify that there is no ‘bgfx’ directory anywhere under /snap/mame nor any of the json files either. I tried manually adding them, but snap has the directory (/snap/mame/1543) mounted as read-only, so I can’t change anything.

Thanks for any help.

Error:
Unable to open effect file bgfx/effects/gui_opaque.json
Unable to open effect file bgfx/effects/gui_blend.json
Unable to open effect file bgfx/effects/gui_multiply.json
Unable to open effect file bgfx/effects/gui_add.json
Unable to open effect file bgfx/effects/screen_opaque.json
Unable to open effect file bgfx/effects/screen_blend.json
Unable to open effect file bgfx/effects/screen_multiply.json
Unable to open effect file bgfx/effects/screen_add.json
Ignoring MAME exception: BGFX: Unable to load required shaders. Please check and reinstall the bgfx folder

Fatal error: BGFX: Unable to load required shaders. Please check and reinstall the bgfx folder

Segmentation fault

Clearly an incomplete built is in snap. I’ve moved on and used the build here:
http://sdlmame.wallyweek.org/repository/