Check that turn guidance is enabled.
Go to "Training" -> "Courses" -> "Course Options". Here "Turn Guidance" needs to be enabled.
plotaroute is an excellent resource for mapping courses. Here's an example of the .txc output for a turn warning 100ft from its turn. plotaroute generates an associative coursepoint for every coursepoint (with a turn).
<CoursePoint> <Name>100ft:Turn</Name> <Time>2021-04-10T03:46:13Z</Time> <Position> <LatitudeDegrees>40.41955433569081</LatitudeDegrees> <LongitudeDegrees>-75.72451157832132</LongitudeDegrees> </Position> <PointType>Right</PointType> <Notes>100 ft - Long Ln.</Notes> </CoursePoint> <CoursePoint> <Name>Long Ln.</Name> <Time>2021-04-10T03:47:33Z</Time> <Position> <LatitudeDegrees>40.41977</LatitudeDegrees> <LongitudeDegrees>-75.72429</LongitudeDegrees> </Position> <PointType>Right</PointType> <Notes>Long Ln.</Notes> </CoursePoint>
Try the following settings for a 520. I've not had any problems with RWGPS created TCX files.
Go to training>courses and load your course. In your Activity Profile check that under Map settings, Guidance text is turned on. (Leave training>courses>course options>turn Guidance=off). Under course settings make sure Course Points = on otherwise no turn by turn cues will be generated.
That should give you a prompt shortly before each turn based on the information embedded in the TCX file.