Blending Overproof to Achieve 40% ABV

[50percent]

Hi

I'm new to this forum, but not to distilling. I have an anomaly that i haven't seen written about here.

I typically produce product from left-overs (pomace, skins, re-constitute) of my wine-making practices. I make wine from scratch, using both California and Canadian grapes.
I am able to standardize finished distillate that is anywhere from 80% ABV to 57% ABV, and bring it down to 50%, or even 48% ABV without difficulty, by simply measuring ABV with a hydrometer-type instrument, calculator, blend filtered water. BUT, if I try to bring the ABV down to 40%, my product turns murky. Sometimes this phenomenon can occur even when attempting to reduce to 45% ABV. It's most peculiar and irritating at the same time, to take two perfectly clear liquids, blend them together, and create a cloudy mess! This doesn't settle or clear: I left a bottle standing for over a year and it remained murky. I have lost some very promising product as a result of this.

Can somebody help me with an explanation / chemistry lesson?? Why is this happening? What can i do to prevent this, and keep my quasi-finished product clear?

Thank you,

50percent