IPAM Audit Events are stored in a separate table from other SolarWinds audit logs, therefor they don't show up there. But all changes to subnets and addresses are stored. As of now there are no out-of-the-box widget for this, but here is the code to build it.
I add a "Custom query widget" to IPAM Summary dashboard. Then add attached code for both "custom SWQL Query" and "Search SWQL Query". Adjust to your liking:
With the search box you can search for date, username or message.