A poster brought up a first paragraph here as more important and the one that says more about real issue here if real of course.

If i remember well it said something like that they run in to technical problems when original milestones were expanded.

So my take is that Ring Oscilator is completed but now they have to build something with it and this is where they run in to problems. As the Team says it is not easy when yoh are doing something for the first time ever and expanding the boundaries of science.

When to expect milestones?

next 3 months

It says it right there;

Team positioned themselves in real time not 31 December 2014.

. The issue was resolved in the last week of March 2015 with the root cause identified as an inappropriate installation by a third party. Appropriate repairs to this equipment have been made. The team is confident to complete the three milestones over the course of the next quarter."