You say that it appears to be working OK and the only fault you report is cold water draining after 5 minutes.
I have a Miele 5170 - it does that same!
Consider that the first sequence is to rinse the crockery with cold water which is then drained out - new water enters and is heated and then at some point the detergent is released.
I think you report a feature rather than a fault.
Good Luck...
April 2016