Soapy_power Empty Outputs

[suciokhan]

System: Raspbian Buster on RPI ver. 4 8GB
soapy_power_ver: 1.6.1
SDR: HackRF

I was able to log outputs using the -O something.csv flag this morning, but now the output file is empty on every run. First I thought maybe my HackRF was fried, but I tried it on my Ubuntu (also soapy_power version 1.6.1) and it populates the output file as expected. I've tried running it with/without sudo and it doesn't make a difference. What is extra strange is the fact it worked earlier, and now it doesn't. I also considered maybe it's a USB issue. I tried running it on the USB 2.0 and 3.0 ports and it doesn't make a difference. I scanned the same bandwidth on the RPI and Ubuntu (90-100 Mhz). I also ran it with the --debug flag, and no scary printouts appeared.

I considered the possibility this is due to a HackRF permissions issue, but I'm able to run hackrf_sweep and it successfully writes the sweep outputs to a file in the same directory that I'm trying to get soapy_power to write to. That would be very strange though- if soapy_power has permission to create the file, I suspect it should have permission to save the outputs to that file it created...

[suciokhan]

UPDATE: I observed that when I disable pyfftw with the --no-pyfftw flag, it generates the outputs. It appears something is wrong with pyfftw; I tried installing the underlying fftw package from the apt repo (sudo apt install fftw-dev) as well as building it from the latest stable release (3.3.9), and neither worked.