It has recently come to light that a relatively small number of drawers of cards have not been indexed (or tagged). This amounts to 2% of the 'soldiers died' pension cards. Specific ranges of names are affected which have been identified. These are detailed in an article on the WFA web site. See here Un-indexed Pension Cards. The 'Missing 22 drawers'
This article also provides a work-around which has been tested and which works.