Thank you, I'll look into it, when I'm back home.
But my first thought is, that it is the positioning, that's making the problems.
The Assembler creates an own stockpile on the interaction spot. The placement of your stockpile will most likely result in an unfortunate cross interaction between both Storages. I'll look if I can place the created storage inside the machine itself, but am unsure, if that's possible. But we'll see..
If this really is the problem then I recommend this:
Stop the production of the assembler and then delete your storage zone near the interaction point. Afterwards start the production again.
If everything went well, this should restart the storage of the assembler without interaction problems.