OK, I’m answering my own Q, this may be a help for others.
I have found that by default the information/metadata displayed with each photo is read from the DK database, not from the photo data embedded in the photo file itself. This explains why external viewers do show a newly added tag, but inside DK that new tag is not shown at all.
I found within in DK Tools > Maintenance > Sync Metadata and Database option, you have the option to write the metadata from the photos to the DK’s database, and vice versa. This will fix the problem which I had.
But I have to ask one thing. Even though I had the option Settings>configure DK>behaviour>scan for new items at startup, and >Rescan files when files are modified, both enabled. This did not appear to do the actual tasks. I tried enabling the option to use ExifTool to do the reading and writing, and backend writing, both to no avail.
So why does the DK not show the data in the photos by default? why does the database not synchronise automatically by default, or at minimum by default write to the database when the app is at idle.
Anyone?
cheers CD