Got it yeah! I contacted Emilie at Mutable and she said turn Meta off. That took some finding but for anyone else with same problem here it is, go to FMCV in the menu settings and click encoder. You can then scroll through various options. META is one of them and although it wasn't set on, the one you need to set it to is FREQ which activates the fine tune knob. Then click encoder again and scroll to SAVE and click and hold that for a second. It should then activate the fine tune whenever you switch on.
Thanks again to all who suggested things. Happy now!