Created attachment 473 [details]
demo device, cable squid, 64 channels, unexpected waveforms

Using 64 logic channels with the demo device results in an unexpected 
waveform display, while 32 channels seem to work, as does sigrok-cli 
terminal output.

How to reproduce:

See the expected output in the terminal.
  $ sigrok-cli -d demo:analog_channels=0:logic_channels=64 \
    -g Logic -c pattern=squid --samples 200 -O ascii:width=200 | less -S

Compare this to the GUI output:
  $ pulseview -d demo:analog_channels=0:logic_channels=64
  (then "configure probes", set the pattern to "squid", capture 200 samples)

Compare this to the GUI with fewer channels:
  $ pulseview -d demo:analog_channels=0:logic_channels=32

I'm not certain whether it's the data display, or the internal storage of 
received data including the zoom level management inside Pulseview.

IIUC the current Pulseview implementation should support up to 64 channels. 
It's a known limitation that more than 64 channels don't work right now.