Problem(s) Encountered:

When we try to close the dropleaf, the warning "ERRO dropleaf still busy" occurred and we can not close the dropleaf remote.

Solution:

Shutter/dropleaf were closed manually on-site by the 2.4m observer.  After this, before leaving home, I checked and noticed all was closed.  I also noticed the error displayed in the log.  I typed:
tx slit stop
which cleared the error flag and was able to cycle both the shutter and dropleaf without issue.