Maybe a little backstory of how the ExP files (allegedly) work will help. Poser normally stores all the morphs for a figure in the figure or as a single "side car" file the "PMD" file. DAZ's ExP instead stores every morph and every dial individually in separate files. This makes the ExP system incredibly frail. Every time you load a V4/M4 Poser has to find all of those files and add them individually. Literally thousands of loose files. What goes wrong is Poser is notorious for not finding things. Give it 3 or 4 thousand things to not find and it's sure to not find something.

So all those morph and dial files are in a not-a-runtime folder.  In the runtime folder for the DAZ figures there's a hidden folder in the Libraries folder. The !DAZ folder. That's where all those thousands of ExP files are really located. Each of the Gen4 figures have their own Batch file. Those _should_ be in that folder too. 

From your OP it seems like that's what you have.

What's most likely happened is some of the !DAZ files are in a different runtime. And, if there's two !DAZ runtimes. That would explain the intermittent behavior. Poser will just use the first one it finds correct or not. You can try searching all your runtimes for files that begin with "InjDeltas." Windows file search can't do it. You need a search utility like "Everything". If you find two of those ExP folders you can just merge them. After you merge the !DAZ ExP folders you will need to re-run all the batch files to rebuild the main injectors.