Streps are well known for sprouting & just sitting there. According to gesneriad whiz, Dale Martens, the key is to move them around. Yes, even at this tiny size she suggests picking them out with a toothpick if necessary & move them slightly. Your perlite is quite large which could be a problem. Next time, sow the seeds on your regular mix with a dusting of fine vermiculite on top or grind up some perlite & mix in. It seems your regular mix is below so you may be able to move some of the large chunks out of the way.

As far as moving them at a young age, I must agree. I've sown many strep seeds & they grew best when I followed Dale's advice. Try not to bury the tiny crown as streps like to grow as king of the hill. Good luck! Terri