One click is not populating the correct serial number for Cat29xxStack devices.
Spectrum by default gets the Serial information from DeviceSerialAttr attribute 0x3d0063 which in turn points to attribute 0x210b5d which is the ChassisId. However in some cases the serial number information is populated in different places for devices.
For the Cat29xxStack (SwCiscoIOS) the NRM_ChasSerialNumber (0x12a6e) is filled from CATStackApp ( chassisSerialNumberString (0x11c01e1)). This is addressed by setting the DeviceSerialAttr (0x3d0063) with the correct values ( NRM_ChasSerialNumber ).
This is addressed via patch Spectrum_10.02.03.PTF_10.2.360 for Spectrum 10.2.3 and is also included in Spectrum 10.3 BMP release
Please contact support to get the PTF patch.