title: Data Validation Drop Down Box Arrow Disappearing
body: <p>I have recently been having issues in one of my Excel sheets, I have created a data validation drop down box that refers to a list in an adjacent column (unhidden). </p>
  
  <p>Until today when I clicked on the cell, the drop down arrow appeared but now it briefly flashes before disappearing again, if you click on the right of the cell it still lets you make the selection but other people will use this sheet so it's not really acceptable. </p>
  
  <p>I have checked that the data validation 'In-cell drop down' box is ticked and I don't know where to go from there, has anyone else had this problem? (Google has not been very helpful).</p>
  
  <p>Thank you</p>