I think what is happening is that most of these are re-skins of creatures available in other books. For instance, the text of the mad golem in the book says: The mad golem is a stone golem with a challenge rating of 12 (8,400 XP) and these changes: The golem is Huge and has 264 (23d12 + 115) hit points. Each of its slam attacks deals 24 (4d8 + 6) bludgeoning damage on a hit. It has Intelligence and Charisma scores of 9. It understands the following languages but can’t speak: Abyssal, Celestial, Common, Draconic, Dwarvish, Elvish, Infernal, and Undercommon. The bore worm follows a similar pattern, referencing another creature with suggested changes. There are only a few actual new creatures added through DMM, as seen in the compendium. I'm guessing the devs didn't think these reskins counted as creatures that needed to be added to the compendium, especially since the base creatures are available in the SRD. This might even be a licensing thing, since the full text of the original monsters is not part of the book and only the reskin modifications are (this is probably why they weren't able to include art on the tokens as well, as there is no original art of the creature included in the book, even if it is a reskin of an existing creature). Your best bet, as Gauss mentioned, is to open a help center ticket, or to use the transmogrifier, or to pull in the base creature from the compendium and make the couple of changes needed to match the reskin text of the DMM adventure.
