Time to do this: 5 minutes
Here was my issue:
Saved a couple lists as templates from Site A
Added list templates to Site B
Created list from template on Site B
Creating new item wasn’t working correctly
In my instance, I had a custom form that would end up creating new items in the list. My list had two required fields: Title and Category.
The category column that was required was a lookup column. The lookup column from the list template wasn’t connected to the other list I had also copied over to Site B. So when I’d use the custom form, the item was getting created in the list, but the category value was empty, so it wouldn’t show up in my custom view.
This is a “duh” moment. A list template doesn’t copy over references to other lists, even if the lists exist on the new target site. List IDs are going to be different, so the custom column in your list template is going to break pretty much every time.
I deleted the category lookup column and recreated it with the same column name/settings.