Why is a bunch of my technology missing?

There was a recent update, where the developers changed a lot of the research sections and items. They have sent out a mail about it, check in game.

Apparently they have combined and changed some research but they claim that no one has lost anything. And they have reduced the money cost of the research.

You should also see some money and diamonds in mails from Last Shelter Studio. Make sure you have updated the game to the latest version.