On MacOS 10.13: High Sierra there is an issue that currently prevents loading Max devices into Live.
We've been in touch with Ableton about this issue and it appears to be related to how 10.13 is handling code-signing of 3rd party apps, in this case Max within Live. The Ableton team is working on a fix as soon as it is available we will let you know.
In the meantime, we recommend that you avoid updating to High Sierra. If you already have, you will need to either downgrade to 10.12 to continue M4L work or to wait for an update to Live.