Not too hot on table saws as I have a RAS, but one thing I do know is that using one without a riving knife is asking for trouble. The teeth rising from under tha table at the back of the blade can catch on the timber either side and start to lift it. What you describe sounds exactly like that - the wood is being lifted by the rear teeth, pushed down by the front teeth, and you're on a roller coaster with no brakes. The ride ends when one set of teeth wins - usually the front because you compensate by pushing the wood harder into the blade - and SMACK! Bye bye insert plate. Put the riving knife back and see if the trouble goes away.
Not sure why your riving knife would be independent of the blade height wise? Seems a design fault or a classic case of RTFM.
Not sure why your riving knife would be independent of the blade height wise? Seems a design fault or a classic case of RTFM.