This is a good point. I usually sell harvestables from the household inventory as inexplicably, they sell for more. I usually use dragon fruit as they sell for a lot. I just had a huge crop of them and it still only let's me sell them by clicking one at a time (I'm on console btw). After 20 years working on computers in my former career and the same amount of time playing Sims daily, I suffer with repetitive strain injury with my wrists and hands so the constant repetitive clicking, well ouch!
Also when moving house if you take the furniture with you, it's soooo slow clearing the household inventory. It lags really really badly. So I don't know if there's a quicker way on PC but on mine that's how it is anyway.
A sell stack option like the one for the personal inventory would be awesome!
What @SheriGR said, yeah. I've found that if I have a stack of eggs and one egg in the stack is spoiled, you can't move ANY of them to the fridge until you find and sell the spoiled egg. Ditto for food that you bought from Zoomers and put in your inventory; if you have an empty plate of the same kind of food you can't drag the stack until you find the empty plate (which will look like all the others) and remove it. In other words: yes, look for a single stuck item, ugh.
I HAVE found that I can sell more than 99 produce items out of an inventory or ICYA chest, but it's INSANELY LAGGY LOL. You'll likely have a very "gluey" cursor with an image of the item for a very long time while the game figures out how to handle it.
