Setup DBI Installer on your switch, open up DBI Installer, open up MTP responder, I believe you need to have the switch driver installed, so you might have to use tegrasmashgui and zadig to troubleshoot that if needed.
your firmware?
where did you get sigpatched?
exfat is good.,mostly they recommended fat32 if the users want to create/search own cheat codes.,
I have two sd cards but the one I often use is exfat without any problems in my games.
Sigpatches are not game specific, they are only firmware specific.
For example:
if you can run 1 nsp installed game but not another installed nsp - it's not an issue with sigpatches.
If you can run 1 installed xci but not another installed xci - once again, not a sigpatches issue.
If you can run installed xci, but not installed nsp - possibly fs patches need updated.
If you can run installed nsp, but not installed xci - possibly es patches or loader patches need updated.