It seems to exclusively happen on the edit form, and not the disp form.
Only way to “force” it seems to be letting clearing the browser cache and loading the full jquery and all other files on the opening of the edit form. That still does not always work either, so I am quite stumped as to the root cause.
All loads of the edit form after this occurs succeed and refreshes work 100% of the time. Until a day or so later it will re-occur to the same user.
It is not what I would call the end of the world kind of error, but it is quite irritating for the users who after filling in the fields at the top of the form need to save and re-edit the file to add items to the vlookups.
How it looks in the UI attached.
The console does not reveal any errors when it happens unfortunately. The child list contains very few items at the moment, and per parent item there might be 1 – 5 items per vlookup in the worst case scenario in the future. So I am not worried about the capacity aspect of this.
Is there a way to add a debugger to the vlookup files? See if they are loaded properly? The rest of the form behaves as it should, even though it is only using tabs and a little bit of css on the labels to make them bold.