It grows here under trees, some areas get very dry, others stay moist. I also have some growing at the foot of a barn wall where it is incredibly dry and sunny -- here it hasn't spread much but grows okay, against the written odds.Maybe it is the ivy's roots that prevent the finer roots of your woodruff from getting a hold?Perhaps try clearing a patch of ivy and giving the woodruff space to get established.
The scent from the drying woodruff was very noticeable in that situation, but also here in this garden, under the trees. I haven't noticed a scent from the patch growing at the foot of the barn wall though.
Other people like it....