Data Validation and Blank Cell Option

Data Validation and Blank Cell Option

I have an Excel spreadsheet that we use for estimation of construction costs.  A key feature of this spreadsheet and used, in many of the cells, is Data Validation with a drop down choice (either from cell range or a list) and I have tried to export this to Zoho Sheet. Most of the spreadsheet exported fine but I had some issues with the Data Validation and decided to re-write the cells.  The problem I am now having is that I need to have a blank cell which is the default, and I need help in doing this.  I have tried to do this using both Cell Range and List but whatever I seem to do the cell refuses to show a blank in the cell.  I have tried it with "Ignore blanks" box ticked and with this box unticked but it makes no difference.  In fact it seems that the "Ignore blanks" box does not, in fact, do anything at all.  
I would appreciate any help that can be offered on this.