I think there is a limitation on the number of settings within a certain time, which may be a Sonos thing. Sometimes the switches are synced within a second, and sometimes they indeed take a few minutes (same switches).
Repeat and shuffle settings possible issue not reproducible anymore in v1.6.0
It seems that when the artist name contains a hyphen (-) the artist name is split across the artist and track tags. See below the example of artist ‘Di-Rect’. Not sure whether this also applies when other special characters are used.