Add me to the list of GD Item Assistant is great.
I think you need to disable cloud saves for Grim Dawn though. That’s a caveat, and one I can live with.
I’ve never had an item lost, never had a problem with it, never even seen any items corrupted. Simply load up the program (it’ll sit in the background) load up Grim Dawn, and when you want to add to IA, drop the items into the nominated stash for storage. If you want the item from Item Assistant, move away from stash in game, alt tab to the program and send the item to the shared stash in game. I can’t remember what it says, but very intuitive. From there, the item will appear in your nominated shared stash box in game.
If you’re really not sure, test it with some yellows first. But I do recommend having all shared stash slots available, and I do recommend checking my note about cloud saves and if they have to be turned off.