Blender material just disappears?

I'm trying to make an animation for my Twitch account in Blender, and I've never really had any major problems since I started using Blender.

This problem only appeared recently. Whenever I go into the rendered view of a material on whatever object, it disappears when I turn the camera (see linked video).

I'm very new to Blender so please don't get complicated answers.

The objects are only rendered from one side.

maybe you have the back

You can change that with str + N in edit mode. You can also border both sides, but I haven't found the setting, haven't used Blender for a long time. But it can actually be found on loan, but still can't find it

I don't think that's the problem, both surfaces are displayed for me without changing anything. Just tried it.

was definitely only like this with blender game.

Anyway, good luck finding a solution

Found a solution.

it half works, but at least I can continue working now.

in fact:

I set the Eevee engine to Cycles.

Now my picture always has to be re-rendered when the camera rotates.

can you change anything?

I'm not familiar with cycles unfortunately