I'm curious how that'd happen for dive machines that have a separate block brake/drop chain from the main lift?
If the video I posted was representative of most the models that have a runout track (usually with a turn) at the top past the lift, there's a physical release for the drop chain dog in the form of a giant metal curve built into the brake area - it doesn't seem likely a train can skip that. The only way I can think of it bypassing the chain dog unlocking mechanism is if the chain dog or drop chain itself is uninstalled.
I don't see operators removing the dogs though, even for maintenance runs - it seems like it would be such a minor part to ensure is installed given the overall complexity of such a ride that there wouldn't be much benefit to testing that way. I also don't really see the point of operating this way if the chain was removed for maintenance either. I'm not sure if any regulatory body would approve operating in this manner either, even if just for test cycles before certifying for the year.