DLC requires its own separate Zrif key, distinct from the base game key. Fix: Repeat the dumping process for the DLC license on your real PS Vita, then in Vita3K, right-click the base game and select Install DLC / License (the process is identical to the main game).
: Legitimate zRIF keys are generated on a hacked PS Vita console using a plugin like NoNpDrm . When a purchased game is launched on an activated console, the plugin creates a "fake" license file that can then be converted into a shareable zRIF string. Zrif Key Vita3k
: Paste the alphanumeric string (the zRIF code) into the text field. Note for Android DLC requires its own separate Zrif key, distinct