Letsie, this might be a problem in other cases, but afais this is not the case here.
Smokes, your problem is easy to fix. Manually change unemployed working classes to HLWs. As in my Country Unimatrix 001 on KB HLWs are the bottleneck in your economy. It is easy to see as when your unemployed HLWs are at a constant 40k this reflects the conversion of max 40k workers from lower classes to HLWs each month. Every HLW above this is allready at work. In large populations this doesn't compensate the natural degredation of HLW number due to retirement/death. So over time all other working classes get larger unemployment while HLW employment is at an effective 100% from the available workers. When there is unemployment in a class of workers, meaning also HTEs and such, there seems to be a conversion from those classes to LLWs. So you see an amassment of LLWs.
With the additional 100k Workers you can change manually down to HLWs each month you might
Thank Borg. This is the way to fix it.
I said earlier today, on another discussion, that we will look into tuning the numbers in corporations a bit, to resolve the problem structurally.
This may have occurred or became more severe in your countries around the time of the servers hardware upgrades but there is no connection.