Ive seen it in the V5 relase notes but I havent seen a tutorial on how to do it.
Add color setting to transparency setting in the action.
Unless the bug was fixed tou need to set the transparency colour in the action and then add that action to a rule, meaning if you want to use that action with different colours you will need to setup different actions
If you add the variable [:Transparency] in the action and try to set the colour from within the rule it doesnt work
Unless this bug was fixed? Ive not seen anything saying it was fixed, i could have missed it though and ive not tested it in the last couple of updates