Using Firefox/Win10/Hookpad+, I am having problems with the various export modes. My original project name had blanks in it and HookPad+ did not want to create a file with the full project name, and would not provide the appropriate file extension (pdf/mid). When I changed the project to a shorter filename without blanks, it did provide the correct file extension for pdf/midi. At the moment, my project is only one line of a song (for which HookPad+ helped a great deal)
The export filenames are not consistently produced and have odd additional words thrown in (like “chorus”). Of the 3 pdf exports, two of them want to produce the same name, and the third wants to call it something like HookPad project.
While testing this, I installed Chrome and switched to it to avoid the stupid yellow “not looking for midi input” message and Chrome works all differently than FireFox for exporting files. All I can say is that project naming and exporting are either buggy, or just not documented appropriately.