Fixed on one site:
Step 1: deactivate all plugins
Step 2: via filemanager/filezilla/ftp delete ALL PLUGINS & WIDGETS not in use. I'm prone to installing, trying, disliking, deactivating. I also had some plugins that didn't work with the current version of WP. I could activate them, but they didn't do anything (specifically King_framework). Messy, messy, much like my housekeeping.
Step 3: I delved into the sql tables. Some of the plugins I've used in the past made their own tables (who knew!).
I "dropped" these tables since I had deleted the plugins/widets in step 2. I first made a backup though!! While I was pretty sure they weren't in use, I wanted to be sure I could plop them back in the db if I was wrong.
Step 4: force upgrade the db. It pops up a few errors, but then says it's successfully upgraded. The errors are probably just housekeeping after dropping tables.
Step 5: delete any previously scheduled posts. I guess you could publish them again, but mine were all tests, so easily ditched
Step 6: set up a future post for a few minutes in the future.
Step 7: Wait...
Step 8: after the alloted time, refresh your blog home page (to run the cron processes). Did the test post publish? Did you wait long enough?
Step 9: after you have successfully published a test entry, start activating the remaining plugins you actually use. You can do it all at once (I did), or one by one if you are worried about conflicts.
Deactivating plugins did not fix the future post problem. Only the combination of dropping unused tables, forcing the upgrade, and deleting the unused plugins/widgets did it.
I would have never braved the sql tables if I didn't do a full site backup first. I also tested the other tables in a second fresh install, so I could figure out what tables were necessary, and which were just taking up space.
I would have never braved the sql tables if I didn’t do a full site backup first. I also tested the other tables in a second fresh install, so I could figure out what tables were necessary, and which were just taking up space.
Keep in mind that the wp-categories table is converted to wp-terms, wp-taxonomy, & wp-relationships when upgrading to 2.3 If you are testing in 2.2x, your sql will have this variance. If you’ve already upgraded to 2.3, do NOT delete the terms, taxonomy & relationship tables. These have the ‘categories’ and the new ‘tags’ feature.
Now I'm off to fix my friends wp install. I hope this helps someone else.