I have an 8 Channel K series, I do this for a living lol. We have had the same issues across the board. More so the 4 channel K series. I have clients that have BT, Sky, VM etc and all have had the same issues, Hence its a firmware issue
Ive usually had to just factory default and they have all worked using the EUI version. Hiks firmware is a bit of a hit and a miss at the moment. Every firmware upgrade i would recommend a full backup and restore back to default.
How did you get this on a K series I have an 8p K series running the last version V4.22.000 build 190821 but cant take it to anyother as i was aware hik pulled the k series from gui 4