I've also just picked up a H240 and ran in to the 'no temperature' issue.
I've figured out from other threads that using the controller type "SAT, auto, 12" driver for SMART actually seems to work better,
using CCISS:
smartctl -H -d cciss,0 /dev/sdb
smartctl 7.1 2019-12-30 r5022 [x86_64-linux-4.19.107-Unraid] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF READ SMART DATA SECTION ===
SMART Status not supported: Incomplete response, ATA output registers missing
SMART overall-health self-assessment test result: PASSED
Warning: This result is based on an Attribute check.
to using SAT:
smartctl -H -d sat,auto,12 /dev/sdb
smartctl 7.1 2019-12-30 r5022 [x86_64-linux-4.19.107-Unraid] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
It's not perfect though, however having kept a periodic eye on the SMART attributes, I can confirm the temperature is changing, I've also noted the power on hours incrementing correctly etc, so I think the attribute data is intact.
BUT, it's still showin * for temperature in the webui...
I'm happy to post diagnostics/any output required, it would nice to get it working as these are crazy cheap at the moment and after putting it in HBA mode, the only thing I had to do is turn off storage boot options in my Asus B450-F bios and it boots/works fine (it's outpacing 6 attached HDDs at the moment!).