Blue Iris not moving through the timeline consistently

[StewartM]

I'm looking for some help with Blue Iris 4.7.7.0. I am unable to move through the timeline without the playback freezing occasionally. This happens with manually moving through the timeline or by clicking 'Next alert'. The image remains frozen indefinitely, sometimes it corrects itself if I move to another point on the timeline.
I5-6500, 8GB RAM, 4TB HDD 10% full, Windows 10 Home.
HIKVision 2MP IP cameras, H264 standard @ 15 frames
Continuous recording, Pre-trigger video buffer 2secs
Combine or Cut video: 1hr, 4GB
Intel HD Hardware Acceleration: ON

Any suggestions?

 

[StewartM]

Forgot to include I set the format to: (for all cameras)