I have a column ( Payment Due ) which will fill up with date if ( Paid by ) is empty.
So when 1st row values is present, it is able to detect result type as date.
however, when ( paid by ) is filled up, ( payment due ) become a blank cell and from time to time, result type is changed to string value.
This will in turn affect rules that set for " Color Column Cells".
This is not how the result type in formula columns works. The result type does not change from time to time. The result type only changes when you manually have the result type redetected.
When you create a formula column, SeaTable reads the column content in the first row. Depending on the value found, the result type is either string, date, or number. You can subsequently modify the values, you can change the sorting, the initially identified result type is unalterable.