LLDB source paths mapping doesn't work

If one sets up Source Paths Mapping for LLDB using standard approach, then it doesn't work: the command doesn't appear in debugger log and stepping inside Qt source code is not performed:

But if one manually adds proper LLDB command in Additional Startup Commands, then it starts working:

The command I'm using is

settings set target.source-map /Users/qt/work/qt "%{CurrentProject:QT_HOST_BINS}/../../Src"
# empty line is important