Update of linked blocks seems buggy.
Open two sessions of rhino one with the linked block and one containing the original block file.
Work on the block file and then in the session containing the linked block click refresh, I found the block updates but if I make another change the block manager sees it and reports it but refresh does nothing.
I found if I have a linked block it will only update once.
In the block manager it sees and says the block needs updating I click refresh the first time the linked block updates but after that no refreshing even though the Block manager says the linked file is newer.