The selected file type should also define the default file extension for saving a file
The Save dialog, by default the filename has the extension .vengi instead of the .vxl extension you picked in previous saves, in this case Tiberian sun vxl, the workaround is to change the extension type in the dropdown to another one and return to the one you wants and the filename is fixed or delete it manually in the filename textbox.
The selected file type should also define the default file extension for saving a file
The Save dialog, by default the filename has the extension
.vengi
instead of the.vxl
extension you picked in previous saves, in this case Tiberian sun vxl, the workaround is to change the extension type in the dropdown to another one and return to the one you wants and the filename is fixed or delete it manually in the filename textbox.