I am already back after several tests in several distros and several teams.
In all my tests I used an AMD PHENOM x4 9950 (it’s already years old) with 8 Gb of DDR2 667 Mhz RAM and two SSD hard drives (one of 120 Gb and another of 240 GB). In all the distros I use GNOME 3 with the NOVEAU driver that comes installed by default (without changes in the software on my part).
The result is:
In Debian, kernel 4.15.0 I can turn off and reset without problems.
In Debian, Kernel 4.16.3 I can reset but not shut down.
In Fedora 28 with the kernel 4.16.8 I can reset but not turn off.
In Fedora 28 with the kernel 4.16.11 I can reset but not turn off.
In Antergos with kernel 4.14.4x I can turn OFF and RESET.
In Antergos with kernel 4.16.11 I can not turn off but reset.
On another computer with the following features I can turn off and reset whatever the software version and the kernel, even with the list that appears before shutting down:
MiniPC with Intel i5 4 Gb of ram (I suppose it is ddr3) and with bios UEFI I do not have those problems.
I deduce therefore that for my team with problems, it may be that some instruction or command of the new kernel will not be compatible with my AWARD BIOS more than 10 years ago.
I’m still looking to see if I see the difference between kernel 4.14.xx and 4.16.xx as soon as it refers to the ACPI system shutdown (or something like that).