Slush pool sent out an e-mail earlier this week stating the pool servers would go under maintenance and the dbase as well. Usually the mining is not affected but you will see the wrong info at the website till everything has updated.
Yeah, but after the maintenance was over, all was the same, I noticed the drop in hash power and workers state today.
In anycase, as I was out of ideas, I logged into the miners again and on the configuration screen, I just re-entered slushpool stratum address >> save and apply and in 15 minutes the Slushpool dashboard showed workers as active.
Quite a weird case, I hope I didn't lose a couple of mining hours like that.