Credit Card Contributions entered by staff listed as complete but never made it to authorizenet
after a lot of exploration it seems that this turns out to be user error caused by confusion about how CiviCRM multisite works. 

The organization has multiple sub-groups, each having its own credit card processor account. The main www site was assumed by staff to be a master that had access to everything, but for the credit card processors it is just another subsite. So staff entering data logged into the main subsite were entering donations for other subsites. Those donations did not vanish, they just went into the wrong bank account.