I'm trying to use M values to create mileage markers every mile along hiking trails in my maps. I have created the trail features to have M values, and have followed the instructions in the online help pages to create shape markers and use the arcade language command $measure to place the markers every mile (1609.344 meters) with the marker placement setting "at measured units". When I do that, nothing appears on my 5-mile long trail.If I use the setting "along the line", or "at ratio positions", the markers show up, but not at measured locations along the trail. Am I doing something wrong, or is ArcGIS Pro 2.3 not dealing well with m values?
The larger image accompanying this query shows the symbology dialog box showing that I selected a shape text symbol, and I used the expression builder to populate the text string. The second image shows the Marker Placement part of the symbology dialog, where I set it for "at measured units", and right now the default is at an interval of 100. I checked, and my linear units are indeed meters, so there should be lots of markers along the trail. I have set the interval also at 1609.344 and also get no markers along the trail.
Any suggestions as to how I might do this (short of breaking the trail into one-mile segments, which would be cumbersome and probably not satisfactory in any way)?