Why doesn't rowing act like running or cycling when one has a structured workouts.

Have you tried creating a workout in Connect using workout? It’ll most likely be available when using ‘Custom’ which means it’s an activity under the ‘Other Sports’. Some features available for the main sports aren’t available for Other even if the watch has a native app for it.

Thanks Frederick.

I'm using Training Peaks to create worksouts as the workout UI in Gsrmin Connect isn't exactly fun to work with.

It seems odd to me when you have an standard activity as "Indoor Rowing" that this doesn't support the features as all other standard activity's.

I get you 100%! It took some time and lots of patience to set up my workouts using Garmin. Then I found out about Training Peaks and Final Surge. I still use Connect because now I just duplicate and change minor details of a workout, but when I have to synch to phone it becomes tedious because of the lack of search bars or filters.