So basically this seems to an issue with a lot of folks... how often does Paradox update their game (in regards to when we can expect this bug to be fixed)? Obviously they just updated today -
Well this is their 5th update since the last DLC (not counting picture/unit/song packs), and the bugs introduced in ROI aren't all ironed out just yet. ROI came out in mid/late March. I've only been playing any Paradox game since last August, but with ROI I've learned to play with Steam in offline mode, as there's a tendency for any patch they release to pretty much break any game I have in progress.
This particular issue seems to have only existed since ROI (well, it's patches) since they are very heavy on optimization for older PCs. But it seems that every patch some older (larger file size) picture files end up in the patch.
While I love the openness and scale of the game, as well as it's modability and being so editable, it really does seem that both of those are needed, as Paradox's quality control doesn't seem to be very good (probably a very small QA team, as they're a smaller studio). It reminds me of when I played MMOs a lot, and you'd have a big, long-awaited patch, and then a patch to fix all the bugs in the patch, then another patch to fix the new bugs the 2nd patch introduced, then a final patch that fixed most big issues, and then a few months of largely bug-free gaming. Only to start the process all over again.
In my brief experience, ROI seems to be the most guilty of being a very shoddy DLC. There are things that were working just fine the day before it came out, but they were changed (to a much buggier version) in ROI for reasons I don't know (I'm sure they have good ones) and three months later are still not fixed. My experiences with ROI, while still quite enjoyable, are not as "good" as they were pre-ROI.