This is a known issue.
For More Information see: FM12 color palette and Inspector: missing 120-color palette for Fill Color
This is one of many acknowledged bugs that can be found in the Known Bug List thread here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: https://www.dropbox.com/s/jt09b82i0xijbu3/FMP%20Bugs.zip
Thanks for the quick response Phil. I'm glad it's not just me.
Are you using FileMaker 12.0v3? (In other words, do you have all the latest updates?)
I'd like to update the info in my DB on this one.
Yes, FileMaker Pro Advanced 12.0v3 (Mac)
Thanks! The accuracy of the Known Bugs List depends on community support as I cannot test every bug every time a new update is released. Input from users when they find that a bug no longer occurs in a new version is particularly needed due to the multiple bug fix releases for FileMaker Pro and Server 12.