@petrockblog, I took a chance, from reading from other posts, to no connect the PowerBlock directly to the RPI but instead run wires to the respective pins. Thanks for the advice as it works as expected with my UPS. Not sure if you've thought about this but I think it would be a good idea to sell the PowerBlock without the black 12 pin connector (as an option) and allow users to solder. I guess users could just solder it off if needed. Anyway. Thanks for you help.
Please do not post a support request without first reading and following the advice in https://retropie.org.uk/forum/topic/3/read-this-first