AC 2 keeps a IPSW cache at ~/Library/Group Containers/K36BKF7T3D.group.com.apple.configurator/Library/Caches/Firmware. Everytime a new iDevice is restored, AC 2 check its cache to see if the latest, signed IPSW is already available at that location. If it is, no need to download a new IPSW, use the existing one. That IPSW can be then be packaged or archived to be shared with others. Boot the problem Mac to DFU, drag/drop the IPSW onto the device in AC 2.
As part of the restore process the IPSW is unpacked to a temporary directory like /System/Volumes/Data/private/var/folders/yf/5l1s2jzx1qlb1_bpszkjjk400000gp/T/com.apple.configurator.xpc.DeviceService/TemporaryItems/82BB4EE1-4BA6-4509-89E2-9DAFE1512A76/Firmware. If you do a restore/revive, delete IPSWs in ~/Library/Group Containers/K36BKF7T3D.group.com.apple.configurator/Library/Caches/Firmware and then restore again, IPSWs most likely will not be downloaded again to the cache directory because the required files already exist in /private/var. To get usable IPSWs in the cache again you may need to go through the process on a different Mac. 2b1af7f3a8