The "Park operation cancelled" Warning message triggered by N.I.N.A. when parking the mount from inside this software has been fixed with the release of a BETA version of the Avalon ASCOM driver that is available with the temporary link below:
https://www.dropbox.com/s/bcfum4a9mjrekev/AvalonStargo_NET%20Setup%207.1.2.3.exe?dl=0
More information on this topic thread.