Hi @Mattcatt, thanks for getting in touch with us. Can you please confirm what Fetch Box you're currently using? We have a handy guide for Gen3 that can assist you further.
Thanks for confirming that for us, @Mattcatt. I'm afraid we don't have a code for Insignia TV (Please view page 8). Since it's a TV from the USA, we have not added it on the list.
However, it's worth trying out the codes similar to your tv brand, Insignia.