No you are not doing anything wrong, that is the state of debugging with LLDB on MacOS.
So #13050 will restore setting breakpoints using the current name mangling scheme in 5.2 and will work nicely with tab complete in LLDB. It’s marked for 5.3 release so fingers crossed it makes it.
Setting breakpoints using filename and line number requires the compiler to output a small amount of DWARF information to associate symbols with source files, and OCaml structures like functions and modules with symbols. Without this you won’t see source code when you hit a breakpoint and list won’t work either. I’m actively working on a fix for this issue.
The problem on macOS with Mach-O binaries is the tooling expects a minimum amount of DWARF information to associate an object file with the pieces of source code used to build that binary. For OCaml purposes that is source file names, mapping from symbols to location ranges and some minimal Debugging Information Entry (abbreviated DIE) to tie everything together.