No Update option for apps that have an update on the App Store

iPhone 5 (MD296E/A)

iOS 9.2.1 (13D15)

32 GB (Capacity: 27.1 GB, available: 8.3 GB)

To reproduce this bug:

1) When the AppStore icon shows that there are updates available, open it.

2) When open, tap on the Updates icon.

3) The list of updatable apps will show "Open" buttons instead of "Update" ones, and the "Update all" option is not available, so the only possible action is to open each of the applications.

4) Push the activation button, to leave the AppStore app running in background.

5) Push the activation button twice to see the list of apps in background and select the AppStore app to make it the active task.

6) You will see the "Update" buttons correctly displaying, but only for a short time, after which, the "Open" buttons will replace the latter.

If you tap on one of the "Update" buttons when showing, the rest will remain and the Update process will develop as normal (including the showing of the "Update all" button). If you wait for the "Open" buttons to appear, you will have no other option but to open your subject-to-update apps.

To me, this is annoying, as sometimes I'm just not fast enough to push the "Update" button when it is displayed, so updating is complicated (I prefer to update as soon as possible over waiting for the automatic update occurs --which sometimes doesn't happens immediately).

Thanks in advance for the support!