Hi I agree with Supthecreek about that this board should ( because I don't own exactly the same board) be more stable while paddling hard to get a wave. That's normal

. This kind of board is made to have stability ( or almost) while standing on the back of the board waiting for the set and to be able to dig rail as much as possible while surfing. They are long enough to have some paddling drive too. While paddling for a wave to take off , getting glide from the front of the board using it as a front planning area to catch wave like any other good surfboard .
About volume factor, IMO, this doesn't mean anything about these boards. It has to float that's all, so ratio must be equal to positive. You will find a dynamic stability while paddling.
Volume is good for buoyant because it's the static thing anchored out the harbour

How to calculate volume factor: Divide volume (unity liter) by your weight + weight of board( kilo) For example Jhon weight 65kg +sunova 6kg= 71
John's Sunova is 80 liters so it's a ratio 80/71 = 1,13.
This why I reckon this SUNOVA 80liters is a perfect board for you.