Why do I missing 1090 Rebroadcast Traffic (ADS-R) Targets from Ground Station as part of 978 Uplink?
Ground stations only send ADS-R/TIS-B messages for targets within a certain distance horizontally and vertically of ADS-B targets with the CDTI (Cockpit Display of Traffic Information, aka "ADS-B In") flag set. Assuming your CDTI flag is set correctly, the targets you're missing probably aren't close enough to qualify.