Not a bug maybe but... hard to explain..

1. Press on item in shopping list, will bring you to another pane to acquire said item...
2. (do not press back), press on other item and the previous pane will remain, hence pressing on shopping list will be useless if cannot see what's behind the pane...

Suggestion: return to main pane after pressing shopping list fires then return with result

In summary, when you search from the shopping list, it should change to the "Buy" tab.

As shopping list are in a tab now, this is no longer relevant