"Spread some items in the chemical synthesiser. Then put some in that line (not a full stack). Then double click the part stack and it picks up all items."
I'd really prefer it if you didn't relate things secondhand, this is just confusing. Either get all the info required by the Bug Reporting Guidelines, or require the person reporting the bug to make the ticket.
"Spread some items in the chemical synthesiser. Then put some in that line (not a full stack). Then double click the part stack and it picks up all items."