there must be something else going on here.
I don't think there's any way to disable macros  based on "time".
Mainly because when excel  is idle, there isn't any macros RUNNING.
so therefore, it can't be monitoring the time.

Do you happen to use any of the Application.EnableEvents = True/False ??
Perhaps you somehow left  the state as "false"...
Or your macro is left in "debug".. in which case, a new macro won't run.

there has to be something like this going on...
Time to do some investigating!