Noticed that in FreeNAS 11.1 U5, smartmontools r4883 are correctly reporting all SAS drive SMART info to GUI and shell. From what i have tested in freenas and truenas, anything past smartctl revision r4883, the drives are reported at 0 degrees C or null in reports and smart queries. Everything worked flawlessly in r4883 and below.
Tested in FreeBSD, CentOS 7 and CentOS 8.
FreeBSD 11.1 U5 and below using smartmontools r4883 and below = working great. (FreeNAS)
Linux using r4883 [x86_64-linux3.10.0-1160.11.1.el7.x86_64] = working great. (CentOS 7)
Linux using r5022 = reporting 0 and nothing past the temps
FreeBSD 12 using smartmontools r5049 [x86_64-linux-4.18.0-240.1.1.el8_3.x86_64] = not working properly.
Seen below comparison screen shots.
Hope this helps and is ok, first ticket i am submitting. I really suspect a scripting change that is not parsing SMART info properly since upgrade from r4883 smartmontools because it did work properly prior to TrueNas12.