I have the same problem. With the ciutric hegemony, even pops from my main species doesnt seem to promote

Temporarily closing the Worker jobs should force the (non-enslaved) citizens to take on specialist jobs. Just restore the jobs once they've done that, so your slaves have a chance to take on the worker jobs. :)

it is because the game prefers the "normal" worker pops for worker role, i think becouse of the happines and approval production plus, and becouse of this, its prefers slaves as unemployed
So anyway, maybe the slavery type change solves it

i solved the problem - it is because of the opression - standart is high - dunno why this is...?
go to your policies, set the opression to none and all unemployed choose the open specialist jobs.
maybe you have to micromanagement a bit, with that, what throki wrote

sorry for my bad english - it is not my motherslanguage ;)

Having the same issue as Mandalore, and I changed the oppression to nothing, didn't fix anything.

About to give up on this mod, between this and the hyperfuel it just feels like they didn't put as much thought into the post 3.0 economy as they should have.

I have 30 open scientist slots and it's been 20 years and I haven't gained any specialists lol... /facepalm

Idk whats going on with yalls mods did yall validate files and reinstall the mods? being serious... I have never had issues like this everything has always worked fine for me