Have you factory-reset the OBi yet, and then re-added it to the portal? If not, try that anyhow. I just tested this with the latest firmware last night, as a matter of fact, and it should simply work.
What you should confirm: after adding the OBi to the portal, you should be at firmware build 4581, and OBiTALK service status should be "Normal", and you should be able to hear yourself on the OBi echo test call.
If you have, and it still doesn't work, then you probably either made some configuration change to the device that broke inbound calling, or you have some sort of home network firewall issue.