Almost everything Aisle does only changes the order of products in a collection. Hiding is the one exception. It takes sold-out products out of the collection instead of pushing them down.
What it does
In a collection's settings, choose Hide sold-out products instead of Move sold-out products to the bottom. From then on, each time Aisle checks that collection, it takes out the products that are sold out.
This affects that one collection and nothing else. The product stays published. It stays in your other collections, in search, and on its own product page. Hiding is on every plan, including Free.
Products with inventory tracking switched off are never treated as sold out, so gift cards, made-to-order and print-on-demand products are never hidden.
Putting products back
Aisle keeps a record of every product it hides, and it only ever puts back a product it hid itself. If you removed a product from a collection by hand, Aisle leaves it out.
When a hidden product is restocked, Aisle puts it back on its next check. That happens even if you have switched hiding off since. A restocked product that stays invisible costs you sales, so switching hiding off never leaves anything stranded.
Hidden products also come back when you switch Keep this collection sorted off, press Remove collection, or press Turn Aisle off. Each of those puts hidden products back first, then sets the collection back to the sort order it had before.
Do one of those before you uninstall.
Shopify removes Aisle's access the moment you uninstall, so after that it can no longer change your collections back. Anything Aisle hid stays hidden until you add it back by hand.
Hiding or moving to the bottom?
Move sold-out products to the bottom when shoppers should still be able to find them — a product that is back in stock next week, a size that is only temporarily gone, anything you are happy for people to see and wait for.
Hide sold-out products when a collection is the shop window and empty listings do damage: a homepage collection, a sale collection where most of the stock has gone, or a small collection where sold-out products fill the first row.
When hiding is not available
A collection that gets its products from another collection cannot have products hidden from it. Aisle tells you: "This collection gets its products from another collection, so Aisle cannot hide products in it. Turn hiding off to sort it instead."
Hiding and putting back both happen on the schedule you set under Check, and never in between. If something sold out or was restocked since the last check, wait for the next one or press Run now.