I've also noticed this on mine when i was fixing it, it would turn off within a few minutes, you know it's the front battery because the central display is dead and the speedo looks half dead/full dead, ignition pos 3 makes no difference until you cycle the ignition key.
I've not tried it recently tho because i drive short distances, got no stop start tho either but i need to do a long run to recharge to get it working i suppose.
Always said the mk7/8 are thirsty on the batteries
We have the environment to think of.
56 350 2.2 130ps mk7 with 2 side doors
65 290 2.2 125ps custom with 2 side doors
07 350 170ps
Ids v86 licence + v86.04 update + xprog
hereIds map
here