TagReadWithGene missing when using latest version of Drop-seq_tools
As per this response from Drop-seq_tools team, at the moment intronic regions cannot be annotated and TagReadWithGeneExon should be used instead.

However, in the version of the public repository:


  TagReadWithGeneExonFunction is the old code, for people who want the more simple tagging methodology and rely on it for 3rd party tools, and TagReadWithGeneFunction, which for your purposes replaces TagReadWithGeneExon. [...]  You’ll see additional options to extract expression for CODING, UTR, INTRONIC reads [...]