I hadn't actually thought to check the MCP logs for my dev environment. Assumed it was the same as the call trace in Composer (noob mistake

). Anyway here's the relevant lines, there's some more information but I'm still unsure exactly what the problem is:
2014-10-23T11:06:15.346 Int 50035 012E0144-10003A48 3148692352 log GVPLOG:sip:dialog@x.x.x.104:5070;voicexml=http://x.x.x.125:80/Fixed-2/src-gen/Main.vxml;gvp.debug=true:calluuid:undefined:gvpsessionid:012E0144-10003A48
2014-10-23T11:06:15.346 Int 50029 012E0144-10003A48 3148692352 form_select :__FORMITEM_NAME_$5923$_:BLOCK
2014-10-23T11:06:15.448 Int 50033 012E0144-10003A48 3144678272 goto :#PlayWelcomeMessage
2014-10-23T11:06:15.449 Int 50030 012E0144-10003A48 3144678272 form_exit normal
2014-10-23T11:06:15.449 Int 50028 012E0144-10003A48 3144678272 form_enter :PlayWelcomeMessage
2014-10-23T11:06:15.449 Int 50029 012E0144-10003A48 3144678272 form_select :PlayWelcomeMessageP0:BLOCK
2014-10-23T11:06:15.824 Int 50029 012E0144-10003A48 3145681792 form_select :ImmediatePlaybackTmpField:FIELD
2014-10-23T11:06:15.874 Int 50024 012E0144-10003A48 3151702912 input_start :VOICE|DTMF
2014-10-23T11:06:15.875 Int 50018 012E0144-10003A48 3152706432 prompt
2014-10-23T11:06:15.876 Std 20003 WARN 012E0144-10003A48-asr-default-27 3065396096 06A007E2 Failed to open an MRCP Session using any of the MRCP Clients.
2014-10-23T11:06:15.876 Std 22017 EROR 012E0144-10003A48-asr-default-27 3065396096 06A007E1 OpenSession failed with all MRCP Client Instances.
2014-10-23T11:06:15.876 Int 50148 012E0144-10003A48 3065396096 asr_open 012E0144-10003A48-asr-default-27|fail
2014-10-23T11:06:15.884 Int 50019 012E0144-10003A48 3152706432 prompt_end asrerror
2014-10-23T11:06:15.884 Int 50025 012E0144-10003A48 3146685312 input_end ERROR|||||
2014-10-23T11:06:15.884 Int 50026 012E0144-10003A48 3146685312 asr_trace ASR_NORESOURCE:results:<Error>
2014-10-23T11:06:15.884 Int 50034 012E0144-10003A48 3146685312 event error.noresource.asr:1|
2014-10-23T11:06:15.885 Int 50080 012E0144-10003A48 3146685312 event_handler_enter :error.noresource.asr|http://x.x.x.125:80/Fixed-2/src-gen/Main.vxml
2014-10-23T11:06:15.995 Int 50035 012E0144-10003A48 3150699392 log com.genesyslab.quality.failure:error.noresource.asr event terminated session
2014-10-23T11:06:16.046 Int 50018 012E0144-10003A48 3152706432 prompt
2014-10-23T11:06:16.058 Int 50043 012E0144-10003A48 3152706432 fetch_end Done (file):file:///opt/SP/genesys/apps/gvp.mediacontrolplatform.8.5.050.40/audio/alaw/default_audio/sorry_there_is_no_asr_resource_available.vox
2014-10-23T11:06:16.058 Int 50134 012E0144-10003A48 3152706432 prompt_play audio|builtin:default_audio/sorry_there_is_no_asr_resource_available.vox
2014-10-23T11:06:18.575 Int 50043 012E0144-10003A48 3152706432 fetch_end Done (file):file:///opt/SP/genesys/apps/gvp.mediacontrolplatform.8.5.050.40/audio/alaw/default_audio/goodbye.vox
2014-10-23T11:06:18.575 Int 50134 012E0144-10003A48 3152706432 prompt_play audio|builtin:default_audio/goodbye.vox
2014-10-23T11:06:19.528 Int 50019 012E0144-10003A48 3152706432 prompt_end done
Any ideas?