I have experience problems with origin/edge nDVR addaptivebitrate streaming. After certain period, automatic switching between bitrates can not happen, ot happen but the video jumps over. It seems that the 2 bitrates which are keyframe synchronized, becomes unsynchronized on the edge server.
what is the period of time that has to elapse for the abr to break with nDVR
As usual please make sure you are running the latest version of Wowza Engine, restart, and reproduce the issue. Then get the conf and logs from the affected server. We may also need the dvr store in use.