I wouldn’t be surprised if there are location reporting issues on macOS, though I haven’t noticed it myself. If you can reproduce it, please attach that to the issue opened.
I expect the missing source locations are caused by a lack of DWARF information on macOS. I have a writeup somewhere of exactly what is required, the short version is ocaml needs to write some DWARF 5 information to associate object files (and symbols) with source files and functions.