I've done a couple extractions with mimosa, enough to say that I think what you're seeing is really, just emulsion. It kinda seems to bubble up and stick in the naptha layer. If this is your problem then add heat to you solution jar. You can place the jar in a pot full of water on the stove and slowly warm till the solutions reaches a temp of at least 110-120 Fahrenheit and keep warm for an hour or two, and repeat if necessary. This helps settle the emulsion.
I hope this is the advice you need...
Peace
"We are all brilliant patterns intricately expressed in a tapestry of one thread." - SolarUnion