I tested Drummer/TreeChart with a massive OPML file (I mind mapped ALL of the settings in iOS 11 just for fun a few years ago). The file name I imported locally had underscores in the name: iOS_11_Settings.opml. However, Drummer made the public URL with spaces: http://drummer.scripting.com/podfeet/iOS 11 Settings.opml. This didn't render in TreeChart, even if I put %20 for the spaces. I tried changing it in the title to have underscores and the base element, but still, it didn't give me a valid URL.
I ended up duplicating the opml file with no spaces, and then it worked on import.
In case you want to see how insane the iOS settings are:
I tested Drummer/TreeChart with a massive OPML file (I mind mapped ALL of the settings in iOS 11 just for fun a few years ago). The file name I imported locally had underscores in the name:
iOS_11_Settings.opml. However, Drummer made the public URL with spaces:http://drummer.scripting.com/podfeet/iOS 11 Settings.opml. This didn't render in TreeChart, even if I put%20for the spaces. I tried changing it in the title to have underscores and the base element, but still, it didn't give me a valid URL.I ended up duplicating the opml file with no spaces, and then it worked on import.
In case you want to see how insane the iOS settings are:
iOS 11 Settings in Tree Chart