Hmm… I went to go look at this in the settings and my SD card is no longer showing up as mounted. I rebooted into Desktop mode and can’t mount & open it there either.
Upon closer inspection, it looks like the skin on my Deck warped/sagged a little around the SD port and seemed to be putting just enough pressure on the end of the SD card to cause issues with the connection inside the port. This may not be the actual issue, but the quick remedy below at least is moving in the right direction.
A few minutes with my wife’s hairdryer and some movement of the Deck’s skin, I’m able to read the card while in Desktop mode. I’m currently backing up all of the card’s contents (mainly saves for emulators) before I boot back into Gaming Mode and test its connection again there.
Side note: kudos to EmuDeck, yet again, for their new export tool. While intended for those migrating to the new OLED Decks, this is very handy for me right now!
Unfortunately, upon further digging, mine was coincidental in it happening around the update time. Mine card was actually corrupted.
With the issue I was having and unable to find a solution, I decided to format it and start from scratch, but it even failed doing that - both with the Deck’s tool and trying again with Windows (simply as a test since the format wouldn’t have been compatible).