Nsight-Compute returns "No kernels were profiled" for multi-process profiling

Hi,
I have two executable files, and I plan to run them concurrently.
Hence, I package the command into a .sh file multi.sh:

./a.out &
./b.out
wait

I used nvprof to profile them successfully:
nvprof --profile-child-processes multi.sh

However, when I use Nsight compute:
sudo ./ncu --target-processes all multi.sh
The return message shows:
==WARNING== No kernels were profiled.

Could you help me identify the issue?