I've now had chance to reset the 8003 and re-configure. The 'invalid parameter' messages disappeared but NTP didn't intiially start working. Here's what I (think) I did in case anyone else finds it useful:
- disabled and then re-enabled daylight saving. Changed timezone and set back to my own local timezone. NTP then started working. Not completely sure of the sequence, but was something like that. Strange.
- then I went to Image>OSD to change the parameters there. As soon as I added my Camera Name I got the invalid parameters error message again. I suspect this may have been the cause of the strange behaviour on Save operations, and may possibly have influenced NTP but I've not tested that rigorously.
So good news is the camera appears now to be working correctly. Bad news is that FTP really doesn't seem to work as
@NoFate has also established. Disappointing as that's my preferred mechanism for getting images back from a remote location. Also disappointing Hik support hasn't come back on this. Guess I'll be waiting for the next firmware release int he hope this gets fixed.
Thanks so much to David and NoFate for their help and support with all of this.