What are the bold deflect and refer to lines below telling me? This worked until last year, not sure if it’s related to 1.6, I can’t nail down a start date.

A ring group rings. When one phone’s FWD button is pressed prior to a call or during a call the call is forwarded to VM extension 2921, and the other phones stopped ringing. This no longer works, the set phone does not ring, the call is not transferred to VM and the other phones keep ringing. I couldn’t find anything on the wiki (it only described using codes to turn FWD on/off), etc. to explain why this stopped working. Any help to get the phone forwarding working again is greatly appreciated. Thanks!
Mario G

YEALINK T48G DSS button is set to forward to 2921, pressing again turns it off. All other DSS keys such as call park, etc work fine.

     <extension name="vmonly">
      <condition field="destination_number" expression="^2921$">
        <!--  Call lua to set early media/ringback, ringtone, bridge parms and voicemail msg, pass the CALLIN function code -->
        <action application="lua" data="/usr/local/FreeSwitch-scripts/known-people.lua CALLIN"/>
        <action application="answer"/>
        <action application="playback" data="${lua_vmmsg}"/>
        <!-- Next line removes default greeting, we already played one above-->
        <action application="set" data="skip_greeting=true"/>
        <action application="voicemail" data="default ${domain_name} 100"/>
      </condition>
    </extension>

This log shows the only lines that contain 2921 in bold:
2016-11-19 16:27:26.673609 [INFO] mod_dialplan_xml.c:637 Processing Mario G <15051234567>->2921 in context public
Dialplan: sofia/internal/15051234567@11.123.1.10 parsing [public->unloop] continue=false
Dialplan: sofia/internal/15051234567@11.123.1.10 Regex (PASS) [unloop] ${unroll_loops}(true) =~ /^true$/ break=on-false
Dialplan: sofia/internal/15051234567@11.123.1.10 Regex (PASS) [unloop] ${sip_looped_call}(true) =~ /^true$/ break=on-false
Dialplan: sofia/internal/15051234567@11.123.1.10 Action deflect(${destination_number}) 
2016-11-19 16:27:26.673609 [DEBUG] switch_core_state_machine.c:286 (sofia/internal/15051234567@11.123.1.10) State Change CS_ROUTING -> CS_EXECUTE
2016-11-19 16:27:26.673609 [DEBUG] switch_core_state_machine.c:643 (sofia/internal/15051234567@11.123.1.10) State ROUTING going to sleep
2016-11-19 16:27:26.673609 [DEBUG] switch_core_state_machine.c:584 (sofia/internal/15051234567@11.123.1.10) Running State Change CS_EXECUTE
2016-11-19 16:27:26.673609 [DEBUG] switch_core_state_machine.c:650 (sofia/internal/15051234567@11.123.1.10) State EXECUTE
2016-11-19 16:27:26.673609 [DEBUG] mod_sofia.c:198 sofia/internal/15051234567@11.123.1.10 SOFIA EXECUTE
2016-11-19 16:27:26.673609 [DEBUG] switch_core_state_machine.c:328 sofia/internal/15051234567@11.123.1.10 Standard EXECUTE
EXECUTE sofia/internal/15051234567@11.123.1.10 deflect(2921)
2016-11-19 16:27:26.673609 [DEBUG] sofia.c:8349 Process REFER to [(null)@2921]