target mode mac pro 2019 not working

Hi,

I am trying to speed up a transfer to my new mac pro using target disk mode as gigbit ethernet will take hours. I got a thunderbolt 2 to 3 connection working but for whatever reason (and i've read this happening elsewhere), the speed was slower than gigabit ethernet.

I finally broke down and put the mac pro into target mode. In target mode, none of its drives mounted for either my mac mini (with a thunderbolt 3 to thunderbolt 2 adapter+ apple thunderbolt cable Nor with a new macbookair with thunderbolt 3 connected directly by thunderbolt 3 cable. In both cases I connected to each in turn of the two top thunderbolt 3 (usb c sized) holes.

It is feeling like it doesn't work. I do indeed get the moving thunderbolt icon on the screen.

Potential variables (I don't want to mess with):

-There is a bootcamp drive. I don't think this hurt me in the past

-I have the Promise R4i in there with about 5 volumes; at least one of those is ExFAT.

Thanks for any help.