Hi @Jimmy,
When SharePoint constructs the list forms, all the fields available for the list item are retrieved from the database. Lists with a large number of Lookup columns might result in complex and potentially intensive SQL Server statements. SharePoint will verify the length of the full SQL Server statement and will display this error message when the maximum allowed length was exceeded:
"The list item could not be displayed/added because the length of the fields was too long. Please shorten the new entries or remove some fields from this list."
To address this issue please reduce the number of columns of the specific list.
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