When you use the reset device on the boss, it won't die. The HP will drop to 0, but she won't die. Her special opening won't happen either. I have found no way to fix this after using the reset device in her arena.

EDIT: This was an issue in 0.10 version, seems to have been fixed now in 0.12 version.

I can confirm this; using the reset lever makes the Hugger-girl boss unkillable (she takes damage but can't be defeated).

Edit: The above only holds for the 0.10 build.  I just now saw the .12 update and will test it out there.

Edit #2: The .12 update appears to fix this on multiple bosses.  Special attack openings may not show up, but bosses are killable, even on reset.