ok I found a bug & fixed it. It wasn't specifically related to the rematching, but it still seems to have been the cause here.
If you had max_unfamiliar_cards set to 0, the first card selected could still be any card you owned instead of just cards you were familiar with.
If you had max_unfamiliar_cards set to 0, the first card selected could still be any card you owned instead of just cards you were familiar with.