Why application suddenly got incompatible with some devices?

Question

I seem to have a serious problem. A few weeks ago I've published an app, Antipaper Notes (com.pancerola.and.antipaper.notes). It is running on API level 11 (Honeycomb), besides that has no requirements. According to the market:

This application is only available to devices with these features, as defined in your application manifest.
Screen layouts: SMALL NORMAL LARGE XLARGE
Required device features
android.hardware.touchscreen
This application is available to over 67 devices. 

A few days ago, I've published updated app as com.subhog.antipaper.notes. I needed to change the package, and there were some important structural changes that justified app separation. However, while the manifest is not changed, people are having problems installing the app. The market says:

This application is only available to devices with these features, as defined in your application manifest.
Screen layouts: SMALL NORMAL LARGE XLARGE
Required device features
android.hardware.touchscreen
android.hardware.screen.portrait
This application is available to over 67 devices.

So the only difference is the portrait mode listed explicite. Now, the weird part. The list of 67 devices is the same. Motorola XOOM is on both lists with the same flavor. However, some (only some!) Xoom users have the application marked as "incompatible with device" and cannot install it.

What can be the cause? If that's the portrait mode, then why does it appear on some tablets and not on the others? If it's something else, why cannot I see any difference?

I'll appreciate any help.

Answer 1

Setting copy protection to "ON" will do this, I've had this happen in my app. It becomes a problem for some users when they receive a system update (Android OS upgrade) by their device manufacturer.