Don't think this is a bug so not posting this there, unknown where to post really!

If you assimilate a city state after you hire troops they have you gain the defender units in their home region AND the hired units permanently. The "quirk" here is if I didn't hire the troops prior to assimilation they simply disappear and no opportunity to hire anymore / prior to assimilation. 

I propose an extra charge / higher influence cost perhaps to accommodate for the troops that have not been hired prior to assimilation or at least some sort of way to be notified that the units that are not hired prior to assimilation will poof. Seems like atm it's not a bug but simply an oddity to the mechanic that if you know you know and if you don't you don't but do now.