It sounds like the named range in WorkbookA is not being saved properly. Here are a few things you can try to fix the issue:

1. Check if the named range is being saved in the correct location: Make sure that the named range is being saved in the correct workbook and worksheet. Sometimes, if you accidentally save the named range in a different workbook or worksheet, it can cause it to disappear.
   
2. Save the workbook after creating the named range: After creating the named range, make sure to save the workbook in order to ensure that the named range is saved properly.
   
3. Check if the named range is being deleted by mistake: It's possible that the named range is being deleted by mistake. Make sure that you are not accidentally deleting the named range when making other changes to the workbook.
   
4. Use a table instead of a named range: Instead of using a named range, you can try using a table in WorkbookA. Tables are dynamic and will automatically update when new data is added. You can then reference the table in your formula in WorkbookB.

To create a table in WorkbookA, select the range of cells that you want to include in the table, then go to the "Insert" tab and click on "Table". Make sure to check the box that says "My table has headers" if your data has headers.

Then, in your formula in WorkbookB, you can reference the table using the following syntax:

Replace "TableName" with the name of your table in WorkbookA.

I hope this helps! Let me know if you have any further questions.