In your case, you should configure the session timeout value in RADIUS no less than 24hrs.
Disable DCD will only made Meraki that not revoke the client in Meraki end.
With DCD enable + client session does not expire:
Endpoint re-associate after power saving mode > Meraki no client record due to DCD enabled > Contact with RADIUS for authentication > RADIUS finds endpoint does not expires in its DB and return successful page (client do NOT needs to key in username and password etc.) > Meraki contains endpoint records again.
As you see, there is no meaningful:
1. Contact RADIUS will extend the association time but no authentication requirement.
2. The successful page prompts out every time after power saving mode, bad user experience.
DCD cannot control RADIUS side, RADIUS gets own timer for each client session.
*** From DCD settings ***
If data-carrier detect is enabled, sessions will be revoked and accounted for whenever a client disassociates from a network. To allow clients to reassociate to the network without re-authorization, do not enable data-carrier detect. See also RFC 2866 §5.10.
***