Thanks it's all the latest version (not beta) I assumed the randomisation was automatic, is that not the case?
you will need to select the random option and use the next brush key it will automatically pick the random brush from the brush set.
and if u press the next key again it will again pick the random brush from the current brush set.
You can check the short gif tutorial here!
Also the GUI issue i will be checking as soon as possible! I will try to recreate in my system and see how to resolve it !
Thanks if you have any issues let me know!