Talkback Help!

Hi All
Regular reader but first time poster
We have two Black Magic ATEM's -
Television Studio HD8 ISO & ATEM Television Studio Pro 4K
We use 2 x Blackmagic Studio Camera 4K Pro with the Studio Converter on each.
I've recently tried and failed to use talkback.
On the HD8 I didn't get very far at all, I had a Sennheiser Broadcast Headset plugged in the XLR5 and was getting audio off the desk but nothing else.
I've then been trying the Studio Pro 4k with a Bose A30 plugged into the desk which operates as expected
. The Sennheiser Broadcast headset plugged into the Camera Pro. The camera operator can't hear me on the Sennheiser headset.
We then plugged a normal pair of headphones into the 3.5mm where the operator can now hear the talkback, but plugging a mic into the equivelant socket on the camera sends no audio talkback to the desk. I've tried the Push to Talk on the function button but that doesn't help at all.
I'm not sure if something isn't compatible, isn't wired properly or what but for something with very little documentation online it's not as plug and play as I hoped!
Any ideas?
Regular reader but first time poster
We have two Black Magic ATEM's -
Television Studio HD8 ISO & ATEM Television Studio Pro 4K
We use 2 x Blackmagic Studio Camera 4K Pro with the Studio Converter on each.
I've recently tried and failed to use talkback.
On the HD8 I didn't get very far at all, I had a Sennheiser Broadcast Headset plugged in the XLR5 and was getting audio off the desk but nothing else.
I've then been trying the Studio Pro 4k with a Bose A30 plugged into the desk which operates as expected
. The Sennheiser Broadcast headset plugged into the Camera Pro. The camera operator can't hear me on the Sennheiser headset.
We then plugged a normal pair of headphones into the 3.5mm where the operator can now hear the talkback, but plugging a mic into the equivelant socket on the camera sends no audio talkback to the desk. I've tried the Push to Talk on the function button but that doesn't help at all.
I'm not sure if something isn't compatible, isn't wired properly or what but for something with very little documentation online it's not as plug and play as I hoped!
Any ideas?