On my CRS-125-24G-1S with S-31DLC20D, the whole SFP info is completely missing after some hours of uptime (all fields are blank in the interface/SFP tab except "module present").
The interface works nevertheless without any issues.
A power cycle (reboot is not enough) temporary solves the problem.
Upgraded to 6.23. DDM data was missing after upgrade/reboot (and was probably missing before) and appeared after extracting/reinserting the SPF module.
LE: DDM info still there after 48 hours with ROS 6.23 (could it be solved?)