"Or use a suitable HDMI splitter - for DV+HDR its a HDFury Diva or for HDR there is a Xcolor HDMI splitter on Amazon (search this site)"
I'm having the same issue with an amazon FireStick, i thought i had purchased the correct splitter https://www.amazon.com/dp/B07WR7KP1B?tag=hyperioforum-21&psc=1&ref=ppx_yo2_dt_b_product_details , and my capture card DIGITNOW Camcorder Streaming Conference Broadcasting .
do you have a link to an acceptable splitter? there are a few that show up with that search on amazon.
thanks