Confirmed - I also had this issue (with AMD Vega 64 v18.8.1) and it was solved by changing the "Hardware Accelerated Decoding" from Automatic to DXVA 2.0.
I tried the above suggestions, but it hasn't helped. The video crashes immediately on seek and freezes about 3/4 of the way thru the 8GB video. Any other suggestions? Would moving to Snow Leopard help?