I am currently working on my master thesis for which I use LuaLaTeX and Helvetica as my main font. I include it like this:
This used to work quite well. Now I bought a new MacBook (with El Capitain preinstalled - my old Mac had the same OS but it was upgraded several times - don't know whether this is part of the problem). Now, luatex can not find Helvetica anymore.
After debugging for quite a while, it seems that luatex does not find the fonts which are packages in a dfont file (even though Helvetica was in a font file on my old mac as well...).
I did not find any solutions to that problem that worked for me (and most other tex.stackexchange questions are about newly installed fonts or system fonts for other operating systems). How can I debug/fix this?