Thanks, I've also just found this older post in the forum, which solves the problem, in case it arises.
"To fix your broken cards, "Search Cards" for "incomplete" cards, then tap "Edit," "Batch," choose a new dictionary under Dictionary / Remap to Dictionary, and tap "Remap now." That will switch those cards over to the new dictionary (assuming Pleco can find entries in it for them)."
Best, Shun