Here is a summary of what I have been doing and how both PM 6 and PM 6 Plus respond.
First, the setup:
1. I have a raw (nef) image file named DSC_3920.nef in a testing folder. There are about 5 raw images and 5 associated jpgs in the folder.
2. I am testing/checking the tag names for each entry in the standard IPTC Template by writing data to each field using exiftool. A typical command entered from the Terminal is
exiftool -xmp:creatorcity="Boston" dsc_3920.xmp
If the sidecar file does not exist, it is created. Otherwise the existing sidecar is modified.
3. the contents of the sidecar can be verified with the command
exiftool dsc_3920.xmp.
4. I then launch PM 6 or PM 6 Plus (with only one or the other loaded at any given time).
5. I click on the "Inf"o button in the lower left corner of the thumbnail image dsc_3920.nef. The IPTC template loads.
6. I click click on "Clear" at the bottom left of the template and then click on "Load" (button beside Clear" A screen comes up asking for the path to the desired sidecar. I chose the path to the image and find the sidecar (in this case dsc_3920.xmp) and open it.
7. In all cases tested to date (all variables above the Art Object table) the input I set in exiftool appears correctly in the expected field in the template.
8. I have performed the reverse tests in which I enter data in the template, save the resulting sidecar, and read that output sidecar in exiftool with the command
exiftool dsc_3920.xmp
This shows me the variable to which that entry is written. It also gives me the correct spelling of the xmp variable name. So far, in all cases there is compete symmetry and data written from either PM or from exiftool are correct and that they are persistent until I send the sidecar file to the trash.
9. These tests indicates that (i) I know the correct xmp name for each variable, (ii) that PM6 and PM 6 Plus both can read sidecars created by exiftool an and (iii) exiftool can be used to operate on the sidecar without affecting data stored in the sidecar.
Now comes the problem:
1. If i enter data into the second field of the Artwork table with
exiftool -xmp:artwork:creator="Leonardo da Vinci" dsc_3920.xmp
the data appears in the correct column of the table. Note the table is left-justified (i.e., the empty Title column is shown; some of the creator column is hidden.
2. Scroll the table to the left and (a) PM 6 freezes. You can click on "quit PM," but nothing happens. The only way out is to Force Quit PM 6. and (b) PM 6 Plus crashes, reloads the screen sending data to Apple and then asking if I want to send a message to CameraBits. I do--yoou should have a couple.
3. If I do not scroll and try to enter the Artwork Creator ID, the table scrolls automatically to try to show the entry, but the programs freezes/crashes.
4. If I restart the program and reload the sidecar without doing any modification to it at all, all the entered date are shown, but if you try to scroll, the programs hang/crash.
5. If I now do this in reverse (with a clean sidecar) and try to enter data in the artwork fields, all data I enter is done correctly so long as I do not scroll the table at all. However, if there is a long entry, whenever I have to scroll in order to enter more information, the programs hang/crash as with exiftool.
I have tried several combinations of using a brand new sidecar having no data except artwork info and loading the data via both the template and with exiftool and get the same results.
This was not an issue with PM 5 so far as I can remember.
HTH
Bob