S4: Pattern unlock changed suddenly to swipe

[AC Question]

I used to have pattern unlock on my Samsung S4. Suddenly, it has changed to swipe unlock without me doing anything. Changing it back (via Settings, My device, Lock screen) does not 'stick'. That is, I can specify the pattern, but after saving it, it still says Swipe.

 

[belodion]

Have you tried Clear Credentials in Settings, Security?