I find it unfortunate that you don’t know the environment in which the uploader works properly.
I have uploaded a huge number of photos so far. But the latest uploaders don’t work properly in my environment.
I think the latest uploader is a failure.
First of all, there are many cases where uploading is not possible.
And the double upload check function, which should have been rigorously checked for over a year, is not working.
In the comments below, I’ve shown a screen capture of how Desktop uploader works in my environment.
http://mapillary.trydiscourse.com/t/desktop-uploader-2-0-2-do-not-work/5160/4
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I want you to try uploading again after a working proper uploader is released.