Currently there is a bug with the delving bench that seems to stop players from putting items in said bench. Players get “cannot place items in this container” or something similar. There is actually a way to still delve.
Enter delving bench.
Select item with x
Move over to delving bench inventory.
Now move up one or two times and it will now highlight the box in the delve spot.
Hit x again and your item should now be in the highlighted box.
Only found one video online and could not find a post when searching forums. Hope this helps.