If you change the format to long you can see that t and Tsol values change. The differential equation settles the last value in 0.001 seconds. The ode45 function seems working correctly. However, if you think the output of the ode45 is not correct, you can check your dTdt = cfunc(t,T) function.
t_interval is the time step of the ode45. Since it solves differential equations, the interval should be bigger than 0. In your function, you are dividing your calculation by t_interval. When you entered 0 time interval the output of the Tsol equals NaN. That's why you see an empty plot.
