Hmmmm... This is tricky, indeed.
If there were leftover alks from your mesc extraction (dissolved in the acetone as fumarate), what you could be seeing is these alks crashing out of the acetone as it dissolves into the alkaline solution and the fumaric acid is neutralised.
Alternatively, it could be the sodium fumarate produced by the neutralisation (insoluble in non polars), although it should readily dissolve into the aqueous layer (unless it's saturated).
Did you keep the cloudy xylene and naphtha? Are they still cloudy? I would evap these solvents and see what they yield. As for the MHRB extract, gently heat it to drive off any acetone that may have mixed with the aqueous layer. Next, you could try doing another pull with clean xylene and see what happens. If it still goes cloudy, your best option may be to filter the bark out and start over (painful though that may sound).
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