FIXED!
Here is what I did.
I lodged a support ticket with Elektron, who were quick to reply and suggested that I send my OT in for repairs. I have gigs this week and next, so I couldn’t be without an OT, and it is close to Christmas so it would most likely take a few weeks there and back with postage. I decided to bite the bullet and get a mk2. Elektron Japan were very nice and helpful and were able to express ship one to me which arrived in 2 days. I am in Hong Kong, so it was quick to arrive. With the mk2 here I felt confident to open up my mk1 and see if there was anything I could fix myself. I have repaired friend’s OT and Rytm before so thought it was worth a shot. Why I didn’t do this before though is because I was convinced it was not a hardware issue. Pins were not bent and it functioned with one card just not with others which made me think it was software related. So I opened up mk1, and removed the CF card reader screws so I could get a cotton bud q-tip in there with 99% alcohol and clean all the pins. I also cleaned all the cable pins on the inside as they give me trouble from time to time. I then reassembled the mk1 and formatted the new cards with the mk2. Then mounted the new card in the mk1. It worked straight away. So, I then inserted the Kingston 16gb which previously wasn’t working in the cleaned mk1. It also worked straight away. I formatted it in the mk1 and it works perfectly. So, the problem was the dirty pins in the mk1. It was an easy fix and one that didn’t require a new OT, but that’s okay. I now have two OT and will figure out how to use both in my setup. Big thanks to Elektron for the quick response and support and thanks to everyone on here for your help.
The short story, dirty pins. I opened it up and cleaned them with 99% alcohol and a q-tip.
The long story, I bought a mk2 so now I am even happier. 