So what you have in the Edit tweak window is something like the below? Show us (copy & paste) exactly everything you have in that tweak window.
Code:
# Order of custom column(s) in edit metadata
metadata_edit_custom_column_order = ['#meta', '#metachecked', '#status', '#last_action_date', '#last_action']
If your window is essentially the same then you need to restore your tweaks to default. Restart calibre, Make sure things are working. Then reenter your tweaks back in one at a time.
Good Luck.