10.3.1 service_plan_addon - There is no such a service plan

[burnley]

Plesk 10.3.1 on CentOS release 5.7 (Final) x86_64
psa-10.3.1-cos5.build1012110718.17
plesk-core-10.12.0-cos5.build1012110629.18

On two Plesk servers we're having problems working with the service plans created after they were upgraded from 9.5.4 to 10.3.1. Some (NOT ALL!) of the service plans can not be used to deploy domains using WHMCS API. For the same plans, /usr/local/psa/bin/service_plan_addon cli tool returns "There is no such a service plan", the return code in the shell is 4. What's interesting is that *ALL* the service plans can be used with zero problems from Plesk panel.
I looked in the psa database in Templates and TmplData tables, trying to spot a possible common characteristic for the service plans for which queries and deployment via WHMCS fail, as opposed to the working ones, but I couldn't notice anything obvious.
How can I investigate this problem further, is Plesk logging useful information anywhere for the event when a service plan is being queried / used via the API? Maybe flicking the magic "debug/verbose" button somewhere in Plesk config? The issue is currently a showstopper for us, we can't automate domains deployment using the API because of it.
Any help will be appreciated.

 

[burnley]

Please disregard the cli-related part of the post, there's also /usr/local/psa/bin/service_plan utility to deal with service plans. I'll get back with the API error in WHMCS.