[BUG] A12X host to A8 guest fails via Apple USB-C to Lightning cable

[badger200]

I'm using an Apple USB-C to Lightning cable. irecovery and libimobiledevice can successfully read device info etc.

iPad Pro 11" A12X iOS 14.4 unc0ver 8.0.2
trying to checkra1n:
iPhone 6 A8 iOS 12.4. (I also have iPhone 6S A9 iOS 13.3 I can try?)

./ra1npoc_iphoneos  -vd
* checkRAIN clone v2.1.4 for iOS by interception
[BUILTIN] v0.12.4
[main] enabled: debug log
[main] Waiting for device in DFU mode...
[io_get_serial] Found serial number!
[main] CONNECTED
[main] CPID: 0x7000, STRG: [iBoot-1992.0.0.1.19]
[main] kpf_flags: 2
[main] enable: verbose boot
[main] bootArgs: rootdev=md0 -v
** exploiting with checkm8
[checkm8_t7000_s8000] reconnecting
[io_reset] ResetDevice: 0
[io_reset] USBDeviceReEnumerate: 0
[checkm8_t7000_s8000] running set_global_state()
[set_global_state] (*) retry: 1
[set_global_state] (*) 0
[set_global_state] (*) retry: 2
[set_global_state] (*) 0
[set_global_state] (*) retry: 3
[set_global_state] (*) 0

The last lines repeat a hundred times but nothing ever happens. Device remains at DFU.