When you have something selected in your mouse, most commonly with me stock pile placement, and you select what will be allowed in a stock pile it does not behave as expected many times reselecting everything to be allowed in the stock pile after the first thing checked was none.
I thought I mentioned this in a post I made prior but I couldn’t find anything.
Workaround is rightclicking to make the cursor the default selection tool and then select what goes in the stockpile.