As I can see I don't have any comment field in my new site, the "discussion settings" looks like this:

And here is my site:
Sorry if you don't understand, it's in Swedish :)

Can it be the theme that doesn't allow it?

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mackiejw Premium
Go to >posts>pick a post>edit
Click on Screen Option (right upper corner)
Check the Comment Box

Below editor is now a comment field
Check if

Allow Comments on this Page is checked.

maxser67 Premium
I had to check in the discussion box also, but thank you very much John! Without your comment I wouldn't find it :)
Travontaz Premium
Some themes don't have comment fields I have no clue why hope this helps.
maxser67 Premium
Thanks. I might change theme then :/