The issue as far as we can see is mainly related to the fact that there were still too many nodes running 1.2.4 at the time of the change in the block rewards, we have not found much else that really sticks out as the cause other than this. I have reverted my wallet back to 1.2.4 along with a few MN's to monitor them for a few hours. Please wait before reverting back to 1.2.4 until I or Silence posts another update. If we find there was some other issue we will let the community know our findings. I would strongly recommend that if you are an FGC holder to check the announcements channel at least once per week. The next update we push will have a spork that requires the next update, if you sleep on that update you will end up with orphaned blocks, something we were trying to avoid with the change over from 1.2.4 to 1.3.0. Thank you for your patience, we will post an update as soon as we can.
LATEST UPDATE:
status update: test net is still running and has gone through several block height / reward changes smoothly, we are waiting now for it to end pow and start pos where we will also watch the change again on pos.