I cannot sign PSBT's with my coldcard. I use the latest version of Sparrow wallet. I manage to save a PSBT file on my sd-card, but when I put the sd-card in my CC and press "ready to sign" it doesn't find the PSBT but says "Coldcard is ready to sign spending transactions".
I have already updated Coldcard firmware to the latest version but it won't help, I have also updated my Sparrow wallet. The SD card has been delivered with my coldcard (so it is from coinkite) and it has been formatted in FAT 32.
Just to throw aside the crazy assumption. Did you insert the microSD card by correct side? Try to pull it out and insert again. PSBT's file might also be not readable on the premise that relevant contacts pins on microSD card were damaged somehow at the attempt to forcefully insert the card into coldcard's slot. Thus, try to use other card.