I have an issue with list lookup if the form is in Display mode.
The form contains some list lookups to another list. The lookup field is set to check a specific view in the source list and filter on a specific value to only return these data to the dropdown.The unfiltered view in the source list contains currently 700 items, the view displays all items at once. This is on-prem version.
The issue is that when opening a form item in View Mode, it is not always able to load the lookup data. For some seconds I see 'Loading...' then it stays blank. When changing to Edit mode it is working, the selections are loading fine.
I have found out that the issue starts appearing for items where the lookup needs to retrieve data beyond approx item#500 in the source list. For testing I've applied a filter to the source list view to get below 500 items, and this resolves the issue.
So, to me it looks as if there is a threshold for display mode? Is that something that can be changed? Or is there another way of working around this issue?