Get  "More than one column DEFAULT constraint specified for column '<column_name', table '& (4250252)

When I try to alter a table, to make one of the columns become NOT NULL, I get an error message saying "More than one column DEFAULT constraint specified for column '<column_name', table '<table_name>'." 

WORKAROUND:
1) Delete the default value for IsFullDay and set it to NOT NULL.
2) Save the changes – no error
3) Alter the Visits table again and set the default value to 0.
4) Save the changes – no error

STATUS:
Waiting for fix to be released in a future version of Toad for SQL Server.