Analogue has just released firmware version 4.7 for the SuperNT that fixes a bug with Super Game Boy. No further details on the issue were given. Also, there’s no v4.7 jailbreak firmware available, so if you were enjoying basic cart support from your SuperNT, it’s best to hold off: https://support.analogue.co/hc/en-us/articles/360000557452-Super-Nt-Firmware-Update-v4-6
As a side note, while I do have mine jailbroken for convenience & testing, I still use my SD2SNES for all SNES gaming. The features are just too overwhelming not to.