I don't know, I wasn't using drills until now, was using Klonan's mining drones instead.
On that matter, mining drones don't recognize newly grown tiberium ore. I asked klonan to add an option for them to rescan for targets, but so far he declined it, so I need to periodically use /mining-depot-rescan.
If you'd put your voice in as the maker of this mod, he may reconsider, or at least add a remote interface for other mods to call a rescan.
The problem with the command is that it also respawns all of the mining drones, and presumably deletes any ore currently deployed drones were carrying.