In the attached model, going to page 2 and right-clicking on the assembly image reveals no "Add Next Step" option, even though there is a subsequent step. Only an "Add Previous Step" option is given.
Going to the third page and choosing "Add Previous Step" inserts the MULTI_STEP BEGIN command *before* page 1's MULTI_STEP END command, causing LPub to crash.
Demo file
Screenshot illustrating problem