Octave snap: Cannot open serial port using the instrument-control package

This command:

serial= serialport("/dev/ttyACM0", 9600)

gives:

error: serialport: Error opening the interface: Operation not permitted

The teminal program putty has no problem with the port. I am in
the group plugdev of the port that has read/write permission.

Octave is started with ‘snap run octave --gui’. Could snap cause the problem?

OS: Linux Mint 19.1
Octave: 6.4.0
instrument-control package: 0.7.0

Thanks!
Jos

I found the cause: it is snap, indeed. An Octave version run without it
works fine with the serial port.