I played at least a good few hours of stronghold yesterday. My group and I did alot of testing in the "fire grate maze" room. The "shorter leash" is definitely related to line of sight. We just changed where we pulled to, and with a bear we beckoned the ranged mobs around corners since they wouldn't follow otherwise. You should be able to clear the room with 3 pulls with practice. It typically took just one extra beckon per pull. I know someone had mentioned bears being useless again, but I think it's just the opposite if you really want to do the roundup method. Bears are the only class that can beckon the ranged mobs around corners.

The king and queen we approached in the same way as before this recent update with one exception. When you retreat to your group, don't run. Go slowly so that she stays within attacking range and she will continue following you. Also don't cut the corner unless/until you have her beckoned to where she can see down the hall. Hope this helps!