On Mac OS X Big Sur using the nRF Connect 1.6.0 installation in Segger the documentation suggest that to add a new source file to a project one should right click the project and select Add New File to CMakeLists.txt. If you do this the file becomes corrupted and the project fails to load again crashing Segger. The problem appear to be that the one or more commands that are expected to be on a single line get split over multiple lines....
target_sources_ifdef(CONFIG_BT_NUS app PRIVATE src/nus_cmd.c)
becomes
target_sources_ifdef
(
CONFIG_BT_NUS
app
PRIVATE
src/nus_cmd.c
)
Reformatting the file then rerunning the configuration utility will correct the problem.