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How to Fix Microsoft Lists Group By Showing NaN Instead of Item Counts

Algirdas Jasaitis Sep 30, 2026 869 views

Question details

Users need to resolve an issue where the Group By feature in Microsoft Lists fails to aggregate data correctly, displaying NaN instead of the total number of items.

How to Fix Microsoft Lists Group By Showing NaN Instead of Item Counts

Product: Microsoft Lists
Device & OS: not provided
Scenario: Grouping items in a Microsoft List view to check aggregated item counts across different categories.
Observed behavior: The item count intermittently displays 'NaN' (Not a Number). This issue may affect only specific lists and can be accompanied by UI changes, such as view tabs reverting to drop-down menus or missing presence indicators.

Before you start

Test the affected list in multiple browsers (such as Chrome and Edge) and the Microsoft Lists desktop app to verify if the issue is a local caching glitch or a persistent backend error.

Solution 1Recommended

Migrate Data to a New List to Resolve Corruption

If the NaN error is isolated to a single list, the underlying data structure or view configuration may be corrupted. Copying your data to a fresh list is the most effective way to restore functionality.

Microsoft Lists can occasionally develop localized corruption affecting specific views or calculation scripts. By exporting and importing the data, you generate a clean list architecture while preserving your records.

Export the affected list

Open the problematic Microsoft List, click on 'Export' in the top command bar, and select 'Export to CSV' or 'Export to Excel'.

Create a new list from the export

Navigate back to the Microsoft Lists home page, click 'New list', and choose 'From Excel' or 'From CSV' depending on your export format.

Map your columns

Upload the exported file and verify that the column types (e.g., Choice, Text, Number) match the original list correctly, then click 'Next' to finalize creation.

Reapply the Group By view

In your new list, click the column header you wish to group by, select 'Group by [Column Name]', and verify that the item counts display correctly instead of NaN.

Migrate Data to a New List to Resolve Corruption

List Settings: Remember to reconfigure any custom permissions or automated Power Automate flows attached to the original list, as these do not transfer during a CSV/Excel export.

Solution 2

Escalate to Microsoft 365 Support for Backend Investigation

Use this solution if the NaN error persists across multiple lists, different browsers, and new list creations, indicating a tenant-wide backend issue.

Free Microsoft Office alternative

Manage and Group Your Data Effectively with WPS Office

If Microsoft Lists is currently experiencing backend issues, you can seamlessly manage, group, and track your organizational data using WPS Spreadsheet. It provides a robust, free, and lightweight alternative to Microsoft Office.

1. Download and install: Get WPS Office for free from the official website and complete the installation on your device.
2. Import your list data: Open WPS Spreadsheet and open the CSV or Excel file you exported from Microsoft Lists.
3. Group and count data: Navigate to the 'Data' tab and use the 'Subtotal' or 'PivotTable' tools to instantly group your records and view accurate item counts.

Fully compatible with Microsoft Excel (.xlsx and .csv) formats for easy data importing from Lists.Powerful built-in Subtotal and PivotTable features to accurately group and count your data without NaN errors.Lightweight architecture ensures fast performance even with large datasets.Free to use with an intuitive, familiar interface that requires zero learning curve.

Frequently Asked Questions

What does 'NaN' mean in a Microsoft Lists view?

NaN stands for 'Not a Number'. It is a standard computing error that appears when a system attempts to calculate a mathematical value (like an aggregate item count) but encounters an invalid data type, a broken script, or corrupted backend architecture.

Why did my Microsoft Lists interface suddenly change alongside the NaN error?

Microsoft dynamically updates its web applications. If a critical bug (like the calculation error causing NaN) occurs, the server might temporarily roll your interface back to a previous, more stable version, which is why view tabs might revert to drop-down lists or presence indicators might disappear.

Will clearing my browser cache resolve the Group By issue?

While clearing your cache is a good troubleshooting step to eliminate local display glitches, the NaN error in Microsoft Lists is typically tied to list corruption or backend server issues. If testing in an Incognito window does not fix it, you will likely need to recreate the list or contact Microsoft support.

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