On Asterisk 16.6.1/PJSIP and using Polycom phones in conjunction with a softphone with the Polycom phones will stop sending registration requests when they receive a response with more than one “Contact” header.
It seems like the Polycom is taking the EXPIRES=582 from the first Contact header and won’t re-register until that time has expired.
Enter a line identification address that the phone uses to register with the server. The address may include a user name, the host of the phone’s SIP URI, or the H.323 ID/extension. For example, if the phone’s line is email@example.com, enter 1002 as the SIP where polycom.com is the server. Or, you can enter firstname.lastname@example.org. Any address entered will be displayed as the phone’s line if the display name and label are not specified.