Yeah I jsut got done following the guide. I am currently downloading something from HBG Shop to see if it worked.HBG only uses eShop dumps, which require one set of patches. Some of the games you installed previously were likely cartridge dumps, which require different patches. Your patches might be mismatched due to the installation of patches from HBG overwriting your previously existing patches, and/or your previously existing patches weren't correct for the HBG dumps. Regardless of what caused your problem, following my steps above exactly should fix your problem.
If your problem is not fixed, the problem could be your games are actually corrupt and/or a problem with your SD card.
Also, again I don't understand how the SD Card might have a problem, in my OP I said, this is happening on ALL 4 of my SD Cards that I use daily with my switch, and It is ALSO happening if I install a game/app to NAND with HBG Shop, not just SD Cards.
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Okay so I just tried to install something super small so it would not take forever, and it worked. So now I am going to try to download/install one of the games that it WAS NOT working with earlier.
If this works, then THANK YOU SO MUCH!... seriously...
I see what you mean that I might have made a mistake or something, but I really don't think I did... because this is the 3rd time I followed this guide step by step, and I did everything the same. so idk....