Sure.

So, in order for a creature to be selectable as a sworn enemy, the ranger needs to destroy 2 weekly growth increments of these creatures, and since dummies have a growth of 0, then 0*2=0. That is, there is nothing to destroy: they are in the list from the very beginning. To solve this problem, it is enough to give them a growth rate >0. It's strange that this bug hasn't been fixed yet.

Here is an archive with the modified dummies (growth rate 1). As they say, feel the difference.