It appears there is an incompatibility in the Memory Configurations between what is in Designer and what is in your Simulator. When this situation occurs, you SHOULD be "locked out" of the "online" features like comparing Memory Image on disk with what is in the PLC. Once you "synchronize" the two, all the "online" functionality would be "restored" ("synchronize" just means you either write the project to the PLC OR you read up the existing PLC project into Designer).
I was able to duplicate it with what SHOULD be COMPATIBLE Memory Configurations, yet I get similar results as you. Hmmmm...
Will investigate.