Hello and thanks for the feedback.
As of v0.3b, the 2204A is now a supported scope, meaning that I've added the code to support it - but it's still untested, so thank you for giving a report. Back on post #2: topic14311.html#p42225
a user reported that he was trying it with a 2204A. But I didn't hear back, so maybe the code updates in 0.3b never worked.
If you could supply the log messages from the log in the application window, I can take a look and see if anything looks suspicious.
In the circumstance where you connect input to output, it actually may be expected that the plot looks noisy. In such a scenario, the gain should be 0dB and phase shift 0 deg. Due to actual noise these will be slightly off from 0/0. Because the application auto-scales the plot, this small noise looks amplified.
For the other DUT, is it something as simple as an RC filter? Can you check it out in the PicoScope Application to ensure that the I/O signals look as you would expect?
Finally, one potentially useful setting the the XML file for this situation is to turn on time domain plots. User DausB reported that turning on that setting caused the application to crash. So, maybe I broke something recently - I haven't tried that setting in a while. Did you try it? If you can get time domain plots, then at least we can see what the time domain data really looks like.
Again, thank you!