Weird effect of mount command in F23

[Richard Ryniker]

I suspect you suffer from software that wants to help you and "Do the
right thing."

If you try to mount a device with no media, mount might simply fail (no
media present).  Instead, at least for optical drives, it presumes the
desired media might be available in the tray and requests the device to
load media, then tries again to mount a file system from this device.

When the drive status changes from empty to loaded, a udev event occurs
that can trigger another piece of software that wants to "Do the right
thing."

I suspect your initial problem results from conflict between these two
programs.  The original mount request fails, whatever operation started
by udev completes, and when you issue a second mount request (for the
now-loaded optical drive) there is no udev event to get in the way and
the mount succeeds.

I do not like to sacrifice well-defined, predictable behavior for
convenience, but others may argue this default behavior serves the
greater good.