This code is the problem in AbstractTabuAcceptor:

while (tabuSequenceList.size() >= maximumTabuListSize) {

Consider these moves:
move 1 (tabu A, tabu B, tabu C)
move 2 (tabu D, tabu E, tabu F, tabu G)
move 3 (tabu A, tabu B)

and a tabu move size of 4, then move 3 isn't seen as tabu with move 1, while it should be!