Borg shields leave your ship with kinda a grid look but leave the borgie bits looking solid. It actually makes a much more subtle appearance than the bright blue framework of standard cloak.
This just happened to me as well. Only the unrefined ore zeroed out but it was still somewhere near 10k dil gone on just one toon. Not sure if other toons were affected as I haven't been keeping an eye on their dil as closely. Ticket submitted.