I found this forum while doing some research on the Lenovo fan speed issue, we have a few hundred MX630 & MX650 V3 Nodes.
Not if this applies for your situation - but you can use/upgrade the BMC to version 4.5.1 XCC Firmware and it should resolve your issue. We also found that upgrading to the "best recipe" for these nodes also fixed the issue. The latest "best recipe" has XCC version 5.1 and it also resolves the issue.
I've included the link to the download - you can upload it through the BMC portal and then update the XCC firmware.
https://datacentersupport.lenovo.com/us/en/downloads/DS569380
Hope this helps! FYI - we didn't have to adjust the UEFI firmware version.
-Vic