Polycom buddy watch works... but at 95% of the time

Maybe is more a Polycom issue but I’m asking just in case I miss something. This issue with Buddy Watch feature happens only when the “buddie” is already on the line and a second call coming. The coworker see the “buddie” line is on the phone but when the second call comes, the LED turn from red to off. After around 15 seconds, when the ringing stop, the line turns red again. No a big problem but is annoying.

The only settings I see in the SIP setting is “Notify ringing”. We use the default value “ON”

We recently moved from Trixbox to FreePBX 13 and this behavior is new since we move. The phones are Polycom 550. We don’t use “Polycom Enhanced BLF” and the Buddy Watch feature works normally. We see this issue only when the phone is already in use. The normal ringing status (when the phone is not in use), is visible on the coworker phone (LED turns red).

In the sip.cfg file we have this line:
<feature feature.1.name=“presence” feature.1.enabled=“1” …

The phones are on Polycom SIP version 3.3.5. We use PJSIP driver.

Someone have an idea where I should look? Thanks!