We are having same issue while using G500 and reconnect. Only in room we are not seeing shared content but other joiners can see the shared content on their laptops.
have you fixed your issue?
I am not sure if you tried over the last 3 months getting this into our support organisation. Posting in this community will not automatically raise this with Poly support as we are all just volunteers here.
If this is only affecting H.323 calls to RealConnect for Teams service, it would be worth checking whether "Enable H.239" (content protocol) is checked under RP Group Series > Admin Settings > Network > Dialing Preference. That feature controls whether a RPGS will be capable of negotiating content capability or not in a H.323 call.