Unable to get gas.py working - Remote IO Error

Hi folks,
On an enviro+ board - when I try running gas.py I get an error with the read_all command on line 79 in gas.py.

Going down the trace, it then says about line 50 (setup), moves into into init (line 92) in i2cdevice-0-0.5-py2.7.egg, before an error in read_register (line 174), as well as _i2c_read

The last line is for x in self._i2c.read_i2c_block_data(self._i2c_address, register, bit_width // self._bit_width) before later telling me it’s a Errno 121 - remote IO error.

All other bits on the board are working ok, the light meter, the temperature and the pressure. Its only the MICS6814 which is being the problem child.

Grateful for whether I have completely missed something.

For info - this is on a new - patched UBUNTU install (pi) and also on a PI 3B - following the relevant tutorial. I will copy a stack trace across - was just working standalone in this instance.

Thanks so much.