GPX tracks are a basis for a map, they are not the map. Therefore, a GPX track will not be shown directly on the map; it is expected to contain all sorts if inaccuracies, signal or quality loss, maybe you relived yourself in the woods along the way - nothing we'd want to have on OSM. The GPX track will also not contain information about the name of the path, the surface quality and other important details we want to record.
What's more, your track might overlap with bits and pieces already in OSM and we certainly don't want a thousand copies of a well-trodden path in OSM just because one thousand people uploaded their GPX!
The expectation is that you will load your GPX track into an OSM editor, and then make manual adjustments to the OSM data based on your GPX track. Basically you'll be "tracing over" the GPX track in OSM, recording the path as it should be, rather than the path with all the (potentially unwanted) details recorded in the GPX.GPX.
If this is too much hassle for you, then perhaps someone else will do this work based on the GPX track you have uploaded. Until that happens, the track will not show on the map.
