The Kin did a quick search, so The Kin isn’t sure if this has been reported. The Kin has a demon summoning dagger on weapon set 1. A bloodlust axe on weapon set 2. Summoning the demon works fine until it kills over from time limit (Honestly, summonable mobs this way shouldn’t have a timer in The Kin’s opinion.)
After the stack limit has been reached however, the demon is summoned and eventually dies off. Both sigils however remain in stasis and inactive and will not “reset” until you zone. What this means is that you can’t summon a demon via the demon summoning sigil, swap to the axe set and stack bloodlust stacks. Neither sigil simply works anymore and you stop gaining charges altogether until you zone.