[I posted what is below, then scrolled back up through this threat and saw Helen's comment about disabling the editor for list view. Could this be the answer to my problem? If so, how do I disable the editor and how do I actually make edits to the List View??]
Thank you! But I found a very strange problem now. The template you sent looked great but I wanted to add a new field.
Changing the Add template was fine, the View Single was fine, but when I changed View List I ended up with the repeated entries being just a string of text (the header was fine - see screenshot). I checked and checked, used code compare, compared the repeated code against the original listtemplate.html in the zip preset file you sent and everything looked fine, just like I'd added 1 more row with a field that was correctly added. I tried this on my own site and on the Moodle test site with the same result.
Then I experimented: on the Moodle test site I created a new DB activity, used your preset, added 2 entries and viewed the list. Everything looked fine. Then I went into the templates, opened the list view template, made no changes but clicked Save Template, went back to list view: everything looked fine.
THEN I went back into templates, opened the list view template, clicked the "See more buttons" option in the WYSIWYG bar, made NO changes, didn't even click inside the editor, clicked save, went back to list view and now the entry was a string of text! Again, this happened on my site AND in the moodle test site.
So all I can conclude is that there must be some bug within the DB activity itself? Perhaps new for Moodle 3.0? The exported template attached is the result of the last step of my experiment - I made no changes to your template at all so it should look identical and I suspect, if you open it once and test it will look fine but if you open the View List editor and make any changes (or just pretend to make changes by expanding the WYSIWYG bar or viewing the HTML) then the List view gets wonky inexplicably (though I'm hoping you can explain it)!
A work around for now might be to just edit the preset html files directly, then zip & upload and never edit them within Moodle but this is obviously a pain, especially since I'm still in development, might need to make multiple changes and will ultimately be using 3-4 copies of the same DB in my course. But if you can solve the problem that would be spectacular!