the block appears to reference itself, when you edit the title sheet (Block A$C6BCF6960), the attributes are contained in it as a block and are also called A$C6BCF6960, so you can't edit them as they are already checked out for editing.
if you edit the block in place, erase everything except the attributes, then explode the attributes, the title sheet re-appears.
Do you know Which CAD system was used to make the block?