Thank you so much for taking the time to reply. These comments are really helpful and have given me a lot to consider and I can begin to experiment again in consideration of all these points. I will experiment with a secondary emulsifier, rapid cool down without mixing, lower emulsification temperature if possible, and @Pharma I do agree the fatty alcohol seems to be working against this emulsion type.
Would magnesium stearate be helpful as a stabiliser here? And should I consider gelling the water phase?
Thanks again everybody!