Hi and welcome here 
Speeds are obviously stored in your file but I have no clue why RouteConverter does not decode the speed tags.
Christian may require your original file instead of a screenshot to look into it.
But time stamps are recorded and stored in your file and RouteConverter has some abilities...
The following screenshots are from a Windows 10 PC. MAC behaviour should be similar.
A *.gpx file with time stamps but no speed:
Mark positions in the position list:
Choice one: Right mouse click -> a context menu pops up
RouteConverter calculates the average speed between the trackpoints:
Don't forget to save the result on PC when you are pleased with it.
Choice two: Menu 'Position'
Speeds are obviously stored in your file but I have no clue why RouteConverter does not decode the speed tags.
Christian may require your original file instead of a screenshot to look into it.
But time stamps are recorded and stored in your file and RouteConverter has some abilities...
The following screenshots are from a Windows 10 PC. MAC behaviour should be similar.
A *.gpx file with time stamps but no speed:
Mark positions in the position list:
Choice one: Right mouse click -> a context menu pops up
RouteConverter calculates the average speed between the trackpoints:
Don't forget to save the result on PC when you are pleased with it.
Choice two: Menu 'Position'
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Matthias
Matthias