Hi, sorry for the late reply.
I am already using Ox version: 5.2.9.14713 (which i believed is the lastest version) when i encountered this issue with max 2019.
Therefore, i am now using max 2018, which seems to work. However, i felt that there's an issue with my massfx as i find my dynamics not as realtime as what is shown in this tutorial
https://www.youtube.com/watch?v=h0U0rC53qXQ
I am just testing on a simple geosphere with a default 300 root count amount of hair guides.
Btw, i was wondering if i could install the Ox version 6 beta on my max 2019 for testing while having the licensed Ox version 5 still running on max 2018 for work?