We've had some trouble with Google that might explain this. We removed two of our logic puzzle apps (Logic Puzzles and Quick Logic Puzzles) from sale recently and replaced them with Logic Grid Puzzles, which has all sizes and difficulties (it is free and comes with 100 new puzzles):
https://play.google.com/store/apps/details?id=com.eggheadgames.lp&pli=1
In the process of removing them from sale, Google seems to have blocked sales of new volumes to people who have the app, but only in some countries. Note that you'll never lose access to what you have already purchased, though the old apps may eventually have problems on new devices as we're no longer updating them.
https://play.google.com/store/apps/details?id=com.eggheadgames.lp&pli=1
In the process of removing them from sale, Google seems to have blocked sales of new volumes to people who have the app, but only in some countries. Note that you'll never lose access to what you have already purchased, though the old apps may eventually have problems on new devices as we're no longer updating them.
We may be able to restore volume sales in your country, but honestly the best approach going forward would be to try the latest app which we are continuing to update and improve. If you do try it and find you prefer the old one, we'd love to understand why so we can improve it.