Noticed a couple of things in IP Groups (Profiles -> Groups -> Create or Edit) on Omada Software controller v5.7.4.  When adding or editing an IP group from the GUI, the IP address doesn't appear to allow the last octet to be zero.

Using the API, it is possible to set a network address with a last octet of zero as expected.  However, there also appears to be a lack of validation in the API which allows setting of an invalid mask for an IP group:

The Cloud controller on version 5.6.43 appears to allow zero as the final octet for an IP group as expected; I have not tested the application of an invalid mask against the cloud API.