1 in 5 Parked Calls drop immediately?

I’m running FreePBX12 with Asterisk 11.21.2.

Around 1 in 5 parked calls are dropping as soon as they are parked. I am seeing the following in the logs. Any ideas what might be happening here?

[2016-08-10 16:25:31] NOTICE[8035] manager.c: 127.0.0.1 failed to authenticate as ‘admin’
[2016-08-10 16:25:32] VERBOSE[8034][C-00000fec] features.c: == Parked SIP/102-00000b3b on 71 (lot default). Will timeout back to extension [from-internal] s, 1 in 120 seconds
[2016-08-10 16:25:32] VERBOSE[8034][C-00000fec] pbx.c: – Added extension ‘71’ priority 1 to parkedcalls
[2016-08-10 16:25:32] VERBOSE[2176] chan_sip.c: == Extension Changed 71[park-hints] new state InUse for Notify User 102
[2016-08-10 16:25:32] VERBOSE[2176] chan_sip.c: == Extension Changed 71[park-hints] new state InUse for Notify User 103
[2016-08-10 16:25:32] VERBOSE[2176] chan_sip.c: == Extension Changed 71[park-hints] new state InUse for Notify User 111
[2016-08-10 16:25:32] VERBOSE[8034][C-00000fec] file.c: – <SIP/102-00000b3b> Playing ‘digits/7.ulaw’ (language ‘en’)
[2016-08-10 16:25:32] VERBOSE[8034][C-00000fec] file.c: – <SIP/102-00000b3b> Playing ‘digits/1.ulaw’ (language ‘en’)
[2016-08-10 16:25:33] VERBOSE[8034][C-00000fec] res_musiconhold.c: – Started music on hold, class ‘default’, on SIP/102-00000b3b
[2016-08-10 16:25:33] VERBOSE[8034][C-00000fec] pbx.c: == Spawn extension (from-internal, s, 1) exited non-zero on ‘Parked/SIP/102-00000b3b’
[2016-08-10 16:25:33] VERBOSE[8034][C-00000fec] pbx.c: – Executing [[email protected]:1] Hangup(“Parked/SIP/102-00000b3b”, “”) in new stack
[2016-08-10 16:25:33] VERBOSE[8034][C-00000fec] pbx.c: == Spawn extension (from-internal, h, 1) exited non-zero on ‘Parked/SIP/102-00000b3b’
[2016-08-10 16:25:34] NOTICE[8037] manager.c: 127.0.0.1 failed to authenticate as ‘admin’
[2016-08-10 16:25:35] VERBOSE[2177] res_musiconhold.c: – Stopped music on hold on SIP/102-00000b3b
[2016-08-10 16:25:35] VERBOSE[2177] features.c: == SIP/102-00000b3b got tired of being parked

I’ve seen this on one system, and the situation was resolved by upgrading to Asterisk 13:
http://wiki.freepbx.org/display/PPS/Changing+Major+Asterisk+Versions+on+the+Fly

stupid question - There are no problems using Asterisk 13 with FreePBX12?

FreePBX 12 supports Asterisk 13.

Great. Thank you