Urgent dissapearing mesh/objects deleted slots (Solved)

The problem is caused because you have removed seating slots from the object but they still exist in the tuning for the object. So the game looks for the seating slots you have removed, can't find them, and so assumes the object is broken and won't allow it to be placed.

To fix this you need to make your own tuning for your objects to use. It's not as complicated as this is going to sound. Wall of text incoming.

Open your object and go to the Warehouse view.
Find and click on any of the Object Definition entries on the left.
On the right, scroll down until you see where it says Tuning.
Copy the text in the box.
Now at the top of Studio click on Tools > Extract Tuning...
In the window that pops up, paste the text into the search bar at the top. You should be left with one result.
Click on the result so that it is selected (blue) and then click "Add to current package" at the bottom of the window.
Close the Export Tuning... window.
Find the new Object Tuning entry on the left and click on it.
Scroll down on the right until you find the line that says <L n="_part_data"> This lists all of the slots that Sims can use.
Looking specifically at your dining table, I can see you have removed b_subroot_2, 3, 5, 7, 8, 10, and 11 so we need to remove those from the tuning as well.
This is the first section of tuning to delete:

You can identify it as b_subroot_2 where it says <T n="enabled">2</T>
Do this for all of the other slots you removed.
Now click the Data tab on the top right.
Where it says Name we need to change the text to make this tuning unique to your object so that it doesn't affect other tables in the game.
Highlight the text in the box and give it a new name in the format of {creatorname}:{objectname date}. Adding the date just helps to make sure the tuning is unique. You may like to add the time as well if you want. You HAVE to include a colon between your creator name and tuning name otherwise it will not work.
Click outside of the text box and the other fields will be updated for you automatically.
Copy the new Name and TuningID. It may be helpful to paste them into a seperate text document for easy access.
Now we have to tell your object to use this new tuning.
The following steps must be done for EVERY Object Definition entry.
Click on the Object Definition.
Scroll down on the right to where it says Tuning.
Paste in the name of your new tuning.
Below, in the TuningID box, paste in the new TuningID.
Once done for all of your Object Definition entries, Save your package and test it in game.

I hope this helped and fixed your problem. If you have any more problems or questions just say.

I can't look at your latest file. Mediafire keeps telling me there was a problem with the upload. Could you try uploading it again?

There is an extra line of code that you need to remove from your tuning for it to work.
Since you got rid of b_subroot_0 you also need to delete the following code part:


It seemed to work fine then. It stayed after placement and seats could be placed up to it. I was in Build mode though so I didn't actually have a Sim try to interact with it.