Why are previous versions of updates not detected when the most recent version is ignored?

Answer

GFI LanGuard's scanning engine is designed to scan for the most recent version of all patches/updates that are determined to be missing. Therefore, if you ignore the most recent version of a patch, LanGuard will report that no missing patches were found (even though there may be a previous version that could be installed.

EXAMPLE:
You have Java version 8.0 update 51 installed.
Since then 2 updates have been released: Java 8.0.60 and 8.0.65.  
When you scan the machine, Java 8.0.65 is discovered as missing
You don't want to deploy this so you either "de-select" the 8.0.65 patch in the scanning profiles editor or choose to "ignore" the patch.
When you re-scan the computer, LanGuard reports no Java patches are missing for that machine (even though patch 8.0.60 could be applied to bring you partially up to date).

NOTE: 
The ability to scan for previous versions has been added as a feature request and may be added in a future version.