This is a real problem. And in the north and in the mound, when the time of the T4 alchemist comes, no one appears for a long time, and then the T1-3 alchemist reappears. Please note that this only applies to the PS4 version. I spent more than a week to catch the T4 alchemist in the places of his appearance, the result is zero. The developer does not want to fix it. On the PS4 now it is impossible to get an alchemist T4. There is an error in the code. In this thread, the guy explains the problem in detail.
If suddenly someone managed to find the T4 alchemist on the PS4, please tell me where.