I received a new Plumeria which seemed to have one or two scale type things on it. I popped them off with my fingernail. Next thing I knew my older healthier Plumie looks like this.
It is 104 here or I would spray it with alcohol.
The white looks like sap from the plumeria leaf where something has been nibbling on the leaves. I would strip off all the infected leaves and watch for new damage on the new emerging leaves. You can use insecticidal soap in the early morning or late evening if you see insects. Don't worry about stripping off a lot of leaves because new ones come in rapidly this time of year.