Comment # 2 on bug 966701 from Michael Chang

It's because the config is loaded by configfile by it's parent config in ESP
and pressing ESC will go back to it, which is command mode because the parent
config does not have any menuentry.

A fix is to start a new normal mode from the grub.cfg in the system's /boot
partition, in that way it won't go back to the parent where the normal mode
rooted.

Here is the /boot/efi/opensuse/grub.cfg fixed the problem for me. 

 set btrfs_relative_path="yes"
 search --fs-uuid --set=root e8048408-27ab-4d44-ad40-1000c0253f83
 set prefix=(${root})/boot/grub2
 normal

Alternatively, to interrupt timeout you could use 'any key' to avoid side
effects of using a defined key (like ESC, 'e' or 'c').