I have a problem after upgrade to ….5.1.1 form 5.1 the add page settings labels is showing, it’s just show the fields and help bottom but no help content or labels for that field, also on admin add pages control is not showing add page option on the menu or left button of the page .

I check that langue settings and it’s English the default language, I have no other language installed and this only happing on the adding page control module,

We have the same problem on all of our 5.1.1. (and 5.1.2) installations

Custom / External modules do not read the local resource files, PERIOD. It's not just that a null reference is returned when a string is not found, it does not find ANY string, even tho the key/value pair is  clearly in the local resource file. The administration language manager CAN read and edit the resource files. But no module will display them.

This does not happen with the standard module resource files.

I made a test module, copied the local resource file of a standard module and changed it appropriately, even this is not working. If I create a local resource file inside visual studio, it's not working. If I use the local resource files from the custom module - it's not working.

THIS IS A MAJOR ISSUE. I don't see whether you even noticed this issue so far?! How can such a thing pass quality assurance?