This is in 18.12.1.
I haven't used MultiGroup since 18.7 or maybe 18.4 and selecting a bunch of clips and selecting MultiClip will create a bunch of separate Group clips and a MultiGroup clip. It now creates one clip with a dot in front of the name.
According to the Help file, this is the expected behaviour:
"Your Avid editing application creates several group clips for each take in the bin, and then creates a multigroup clip from the groups. The multigroup clip has the same icon as the group clips, but the icon is preceded by a plus sign."