I've already traded away so many picks that the 12th is actually relevant to me.
But the 12th round pick is not part of the picks pool we actually have. It's only up to 11 rounds, and the rest are used as placeholders for even draft pick trades. If you lack your 11 round picks, then it goes by Supplementary round picks, not Yahoo rounds 12-20 picks.
h. Teams who would not have a full roster following the regular draft rounds will receive supplementary draft picks. If a team protects fewer than 9 keepers, then they will receive supplementary picks of Type A equal to the number of keeper spots they failed to use. If this is still insufficient to provide a team with the opportunity to draft a full roster, then they will receive Type B picks as required until a 20-man roster can be filled.
In this case, the regular draft rounds are rounds 1-11, if you do not complete a team of 20 players after those rounds, then you receive supplementary picks as listed in the CBA.
Please let me know if this is not clear.