TOPIC: Ioun Stone Cap

Player guide says 9, but TD Character creator has let me add 5 extra slots for 10 total. Just want to confirm! Thanks!

I think that version of the PHB is just out of date. It was last updated in six years ago in 2019.

As far as I know, the caps should be:

Charms: 10
Iouns: 9
Beads: 8

Edit, my copy of the PHB from 2023 says this:

There are several items which can increase the number of charms and/or ioun stones you may equip, but you may not equip more than 10 charms nor more than 9 ioun stones.

App is wrong - consult the TDb descriptions for the tokens you are equipping, e.g.:

Earcuff of Orbits says explicitly:

This item’s effect stacks with other Ioun Stone slot-expanders, but the wearer is still subject to the Slot Expanders Cap of no more than nine Ioun Stones.

It may be a new issue for the app, because at the time these limits were created that was they were the maximum number of slots achievable - however things have changed since then with Followers and the upgrade wrist charm expanders (and Minor Orbits I guess? - probably some other stuff...)