When adding a folder/project to a task in the task info window the search depth/scope of that feature is extremely limited.
It appears to only search 2 or 3 layers deep in the project tree. If a task rolls up to the top level project through a subtask or two and then a folder then the project Wrike won't find it. The same isn't true of the search at the top of the main screen.
Love the add to a folder feature but trying to do this by tagging some higher level folder and then going to the Gantt to move down the tree and assign it to the correct lower level folder is tedious.