With a 24 run mixture DOE I could find very good models and optimal settings for a ternary mixture and one categorical effect, this was presented in foregoing discussion; find in attachment again the analysis and below screenshots of the desirability results.

With Isomer 2 desirability result is worse; below the settings when locking Isomer 2

Starting with a 9 run candidate space filling set (see attachment Succesful 9 run) set or a 12 run Kowalski set the optimal settings with Isomer 1 can be detected.
However starting from a 6 run space filling candidate set I always get the poorer optimal settings with Isomer 2, even after several added space filling runs! What did I do wrong and how to get from this 6 run candidate the optimal Isomer 1 settings?