Why do monsters do more damage when I shield block?

[Farzinz]

I tried this with a couple of characters in Meridia.

If I do nothing the damage range from a monster was 7-14. When I shield blocked against the same monster (even though my DR was well over 14), I was constantly taking 1-2 damage. The Combat log showed the monster constantly doing over 20 damage and then subtracting my DR.

The same applied when I equipped and Item that provided DR 5/-. The monster started doing roughly 3-4 more damage.
I tried Stoneskin and the monster started doing more damage.

Is this a known issue, has anyone else tried this and noticed it?

[Zirun]

Dungeon Scaling.

DR applies to the damage before scaling takes effect, so DR seems to do less when things are scaled.