returns empty collection array when using GPX files with tracks but don't include UTF-8 encoding


  I'm new to Fiona and geospatial in general but so far I have been able to open 90% of GPX files and use transform_geom to get geojson formatted and returned from an endpoint. My issue is that occasionally certain files seem to open correctly but contain no data but I know the GPX file has data. I can't figure out what the issue is... these files both open fine in qgis so I know they are somewhat valid. Any ideas?

I've attached two examples.
Here's what I use to open the files:, layer='tracks') ... I also tried:, layer='track_points')