I'm having a bit of an issue syncing a list. I've just installed the component, entered my API key and set up webhooks as in your documentation. When I go to Sync Lists it successfully shows the list. However, when I tick it and click Synchronize, it processes briefly and then shows 'Null Undefined' above the list ID and nothing more happens. When i close the List Synchronisation window, I still see 'You don't have any synced lists yet. Sync your lists now by clicking the sync button.'

I've checked on the Mailchimp API calls list and I can see the call is being made successfully. There are many lines showing:

Date/Time  Result  Throttled?  Source IP  Method  Format  Exec Time  User Agent  Ver  Response
2014-04-24 16:38:52 GMT {tick} nope 217.***.***.70 lists php 0.039s MCAPI/1.3 1.3 n/a
2014-04-24 16:38:50 GMT {tick} nope 217.***.***.70 lists php 0.04s MCAPI/1.3 1.3 n/a
2014-04-24 16:34:01 GMT {tick} nope 217.***.***.70 lists php 0.039s MCAPI/1.3 1.3 n/a
2014-04-24 16:33:59 GMT {tick} nope 217.***.***.70 lists php 0.039s MCAPI/1.3 1.3 n/a
2014-04-24 16:29:46 GMT {tick} nope 217.***.***.70 lists php 0.045s MCAPI/1.3 1.3 n/a

Any idea why this might be?