The validation fails if a IPv6 address is entered. Also, having IPv6 enabled, breaks Bamboo IP Whitelisting.

The following error is returned when the build is triggered:

<errors>
<error>Build request for plan "My Plan" originated from 127.0.0.1,0:0:0:0:0:0:0:1 which is not an allowed address (one of[, 127.0.0.1]).</error>
</errors>

Workaround

If IPv6 is enabled on the Bamboo server, it can be disabled to workaround this issue.