Formulas disappearing and replced by values

There appears to be a pattern of failure developing in an excel worksheet that is interfaced in any way to outside data. Whether it is a table or simply vba pouring data into the sheet from a text file. In the case of the table the Custom Views feature becomes disabled. In the case of text file data being added to the worksheet through vba, it's the formula that is disappearing from the cell and reverting to a static value. I originally thought it might be a memory problem but my trials have disproved that theory.
My workaround has been to programmatically refresh the formulas in any cell located on the affected sheet.

Originally Posted by SDruley

In the case of the table the Custom Views feature becomes disabled.

That’s a known limitation of Excel.