Hi @BT
Does this issue occurs with all Excel workbooks?
Generally, this error caused by data validation in the sheet for specific data values only.
Please select the cell or cells where this happens > Go to Data tab > Click Data Validation (In the Data Tools group) > Check whether there is a validation rule set?
If you want to remove the validation rule, please tick the box of 'Apply these changes to all other cells with the same settings', click 'Clear All'.
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