Can someone explain gtw scientist serums’ “untested” status?

As far as I've seen in my saves, you need to test a serum 3 times. So, make 3, ask other sims (or I guess you could drink them yourself, that should also count for "testing" purposes) to test them. The next serums you make should show "tested" status. Not counting any bugs or other weirdness, that's how it should work.

And I don't think cloned serums work. You'd have to actually make them yourself. I'm guessing it has to do with the cloned serums being the exact copies of ONE "untested" serum.