Booting time change between manual selection and default boot

[chocho 92]

Hi everyone,

I've just made a fresh install of linux mint on my pc on a new ssd without any other operating system, and I've got a strange issue that I can't get ride of it.

If I let the pc boots alone it takes times and in the dmesg output we can see that the boot process get stuck 64 seconds (between line 527 and 528)

dmesg output : paste.debian.net/hidden/3c25f07f

Whereas if I hold the shift key to enter into the grub menu and then just press enter to select the first line, it boots in no times.

dmesg ouptut : paste.debian.net/hidden/acfc3eca

The content of the /etc/default/grub file : paste.debian.net/hidden/1d6ecbc1

For my point of view I was expecting the same result since the default boot choice is the same than the one I made manually.

I can't figure out why there is this change of behavior.

If anyone can explain me what I've got wrong, to try to solved this boot delay.
Thanks a lot in advance.

Vincent