On my Create: Above & Beyond server, I have a storage system that hinges partially on a row of drawers powered by a single Drawer Controller. When trying to insert items into the Drawer Controller via a Pretty Pipes system, some drawers can be inserted to, while some can't, and it's pretty much random which ones are functional and which ones aren't. However, if you connect them directly instead of over the Controller, they are recognised.

[First described here, issue has been since further examined.]