I searched briefly but didn't see a thread... I'm guessing this has been discussed multiple times but wasn't sure where. If I've been too cursory with my searching, feel free to let me have it :-)

Sometimes (or even often) flights show a seat map that don't seem to match inventory.
Example: 1/4/2020, UA102.

Seat map shows eleven available seats to choose, but inventory reflects J4. Does this mean seven seat assignments haven't been made but that only four are available to sell? Or are there seven in the upgrade queue? (But wouldn't PZ inventory reflect availability?)

At the end of the day, the question would just be: is it safer to look at inventory or the seat map to gauge upgrade clearing chances?