Try restarting studio, and trying again. Another possible solution is to update roblox studio. If this is still occurring, uninstall roblox studio and install it back. Or just shutdown all of your game servers, then try.
Because if it is 2,200 items, then you might’ve accidentally duplicated all of the items. I’m sure that might be possible (or it’s just me, I froze Studio twice since I accidentally cloned everything holding CTRL+A).
If it is parts, since if you can start grouping some parts together.