I think this is due to some changes we made with regards to fetching dbms output.
To work around it in 16.2, try this.
While Toad is not running, edit Toad.ini with notepad.
Add this under [SETTINGS]
FetchDBMSOutputByLob=0
Save and close Toad.ini, and try again in Toad.
I believe this is fixed in the beta, which you can get here.
If you do get the beta, please let me know if it is fixed there (w/o the Toad.ini workaround)