When I create a map with tag groups and colours and then try to set up a map roll-up to a new map, the tag groups and colours both disappear in the roll-up map. The tags are all lumped, uncoloured, into the General Tags group and can't be edited (this is some of the same behaviour that Nordman has also reported on recently).
This happens even if you copy the tag groups across from the source map to the prospective roll-up map's Map Index prior to creating the actual roll-ups. This undermines the usefulness of roll-up maps.
There is a similar issue when just copying a branch to a new map. If you first copy the tag groups into the new map's Marker Index the tag groups and colours will be recognised, but only at the main topic level. Any tags belonging to tag groups on subtopics are again put uncoloured into the General Tags group.
And if you don't copy the tag groups across first all the tags, including those at main topic level, end up uncoloured and ungrouped in the General Tags group.