I have another question regarding block and it may be related to my file.
If I don't have the 'stab-rib-top' layer visible and I select the block 'rib-1' and then click the 'edit block' button the entity is not visible. If I make the 'stab-rib-top' layer visible I can see the block entity for editing. [EDIT: figures this one out, the rib outline was in the stab-rib-top layer, odd thing is that it would not disappear when the stab-rib-top layer was made invisible. Could be I had a mix of entities in the block...? ]
I also noticed that after editing a block and closing the editor the main drawing doesn't show the results necessarily. If I click on block 'rib-1' and click on the edit button and delete the inside edge line(s) and the click on the 'x' of the block edit window the change does not seem to have happened. If I close the file and reopen it the change shows up.
Before going to block edit on the rib1 block
After removing the inside line
After closing the block edit window.