I have an idea of how you might be able to fix that. delete it from user/addcont, then backup the app.db from system_data/priv/mms . after that, rebuild the database. it shouldn't find the dlc then. your games will be gone if they were fpkg, so reinject the app.db, then restart the system or log out of the profile you're in and log back in. your games should be back. I don't think dlc is affected by rebuilding the database, but I don't know for 100%.
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if dlc is affected, just reinstall it. I'll see if I can figure out if it is tomorrow morning by counting how many dlc's I have compared with the packages (backed up all of them). I hope he backed up his.