Hi,
closely related to this: viewtopic.php?f=4&t=9800
the folders have sync rules in a dropbox folder. I just checked a few of those with a red exclamation mark: the sync file randomly changed.
it changed
from "/volumes/external backup/dropbox/hazel/pdf.hazelrules"
to "/volumes/testme/docs/pdf/new contract agreement.pdf"
I have no idea why. And this triggers the link above as long as hazel is running.