<p>Ah, of course they are stale. They are set by the NS not by the NA. <a href="https://github.com/RIOT-OS/RIOT/pull/3892" class="issue-link" title="gnrc_sixlowpan_nd: activate NC state machine">#3892</a> is the full fix then (not for the disappearance though... that's still strange and we have to look into it, but my fix makes that harder, since entries are more seldom STALE now ^^)</p>

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