I am really baffled by this one.
To be fair, in 1.26 I made a change to the way singleplayer worlds list gets populated (you may have noticed the “scanning worlds” box). But for the life of me I don’t see a way this could have screwed things up. And I looked long and hard.
Anyway, I have reverted to the old method just for testing purposes and made a new apk:
This is an APK of Survivalcraft Demo 184.108.40.206, with the old method restored.
If you are experiencing the blank world names problem, could you please download and install this APK, and see if the problem goes away? Thanks!