Neighbors (ARP-NDP): Add Static neighbor - Is the static limit only 16 entries?

XG310

SFOS 17.5.4 MR-4-1

What is the limit of the static neighbor table?

The reason I ask is that it only seems to let me at 16 static entries. When trying to add the 17th entry it just gives me the spinning image for a second then stays on the add screen without actually adding it to the table.