Am I missing something? To upgrade to Anti Seizure it requires the catalyst and the 15-18.
So you get it to 15 which now has a tick and get the catalyst yet you still have to put it through another Agglomerator to get it to 18 according to the tutorial. But why? When the requirement clearly states 15-18. If not, why not just make it 18 and remove the 15 requirement.
The concentration and catalyst requirements must be met.
While the requirements are met, it must be sent through the upgrading machine.
When you have the 15 concentration and the catalyst, you are done with step 1. However, to actually upgrade it you must complete step 2. In this case, you must use an agglomerator to upgrade it. No matter what machine you use to get it within the 15-18 range, you will need to agglomerate it afterwards to upgrade it.
Getting the concentration from 15 to 18 is not a requirement for upgrading. You can use the Agglomerator to upgrade the drug while its concentration is at any point within the upgrade range and the catalyst is present. The concentration after the upgrade does not need to be within that range.
Also the order in which requirements are met is not important. You can mix in the catalyst first and then bring the concentration into the upgrade range. The catalyst will get the tick as soon as it is mixed in. It is only important that all requirements are met at the time you put the drug into the upgrading machine.