There's a GPS Beta update for the Sony GPS chipset used in the Marq here: https://www8.garmin.com/support/download_details.jsp?id=14947
From the release notes:
Change History
Changes made from version 2.30 to 2.42:
- Improved GPS performance and reported distance for open water swim activity.
- Improved performance in GPS + GALILEO mode.
- Improved GPS performance for auto-racing activity.
- Other bug fixes and improvements.