As a workaround to make this work in the current version, edit the aws.cfg and look for the <Regions> section. At the end of that section, append the following:
<14>
name=EU (London) Region
code=eu-west-2
</14>
<15>
name=US East (Ohio) Region
code=us-east-2
</15>
<16>
name=Canada (Central) Region
code=ca-central-1
</16>
Restart the probe after this, and it should be able to discover the EC2 instances in those regions.