Hello and welcome to the Conan Exiles forums.
there is not enough information to help you.
What type of server are you playing on ? pvp/pvec/pve?
Do you play on a server or solo / coop? .
it is possible that the decrease of the enslaved njs is activated and that following a long absence, the njs simply died of starvation, if I do not say anything stupid the timer is 15 days (to be checked)