If you link a wireless block extender to something (for example, a chest), then start inserting items into the wireless block extender (I used a hopper), and then break the chest that it's linked to, really bad things happen: the wireless block extender will still accept items and insert them into the inventory that no longer really exists, essentially voiding the items (I also started having really weird desync inventory issues, but I'm not totally sure if that's related).

Note: it will then always insert items into the non-existent inventory until you re-link the wireless block extender or reload.

Unless I'm mistaken, the fix for this might be to basically recheck the connection every time a connection is attempted to be used (every single item/fluid/power transaction), as I'm not sure if there's a way to remotely 'subscribe' to block updates of non-neighbor blocks.