It looks like there's a visual bug in Dashboard > Listings -> Item Edit. When the edit page is loaded, the User information (on the right) is often wrong, especially when you edited some other listing before (the fields hold the previous values or some values are missing/empty). This can be fixed by refreshing the page. Did anyone come across this bug? 

Send guide how to reproduce on demo.

I don't think I can use demo -- it says themes demo site mode enabled, you cannot access this section.

Anyway steps to reproduce are simple (possibly Item Validation plugin is involved, so keep that in mind):

1. Go to the dashboard > listings.
2. Click Edit link that you see on some listing.
3. The Edit page will open, and on the right you have the User information,  Item location, etc boxes.
4. Make changes to the any fields in Item location for instance
5. Save
6. Go Edit another list.
7. Some fields will be filled with the values from the previously edited listing.
8. Don't edit the second listing -- just refresh the page
9. The values in the boxes on the right should be different and reflect the state of the database.

@morfik
Did what you wrote (suppose in backoffice) and could not reproduce.

Backoffice/dashboard one thing.

I don't know why this happens, but it looks like that my friend also has this issue -- so it's confirmed by more people.

Sometimes the city field is filled, but often is set to empty even when the city is set in the database and is visible in the listing (and searching by it returns results). The same with phone numbers. Sometimes they reflect the real phone (set by the user), sometimes the phone is set to a different one (while editing the listing).

When I edited the text of some user's ad, the edition also changed his phone number to the one of used in some other ad -- I didn't touch the number, I just fixed the text. The user sent us an email with this information and that's how we targeted this.

I looked into the database, and saw many listings having the same phone number -- all of them were edited after adding more cities to the database. So clearly something is wrong with editing.

Sometimes when the page is refreshed the proper entries are returned, but as my friend said to me, in his case this refreshing does nothing, so it doesn't work for him. It worked a few times for me, but it's not 100% thing. But the data in the user/location fields in the edit often doesn't reflect what is in the database, and I don't know where the data comes from...

@morfik
Osclass tries to store data before edit into session (when you hit edit/save button) and when there is PHP error, tries to restore form using these data.
Anyway at the end, all of them should be cleaned. This is what is probably happening on your end, that session is not cleaned. Maybe cause by some plugin?

Possibly, but I don't know how to debug this to find out which one plugin may cause this.

@morifk
disable all and try.
then enable one by one

I try this later and see whether there's any change.