Stone blocks not installed

This is unfortunately a technical limitation of the old version Blocks are basically placed in a fixed grid, and only one block can be placed inside a "cell".

The new version doesn't suffer from this limitation anymore btw, so there you wouldn't run into such issues

Having that said, one thing you could do in the old version is removing the triangle blocks and place full blocks there instead. That would work from a visual point of view, but that wouldn't help if you want two different textures / materials in a single cell.

Quote from drsound

Hey ! Such a thing ... I don’t even know if this is the norm or a glitch ... In general, I can’t finish building the house, because it’s impossible to install one stone block on another. In the game, any blocks are ideally suited to each other, but in my case, in specific situations, well, no way! .. I don't know what could be the matter! Has anyone experienced similar? Let me know if there is any solution. The construction of the house is not completed! And I would not want to change the design of the house for the sake of "the will of the game"! Here are some screenshots showing the problem.

P.S I apologize for the possible clumsiness of the text ... I'm not English-speaking, I use a translator

In the old Java Version the typical blocks always cover a cube of 1x1x1 - no matter which shape they have. In your example you have placed a triangle block but as for the game this triangle block occupies a full cube block.

A workaround would be to use the planks and beams.

But honestly, i strongly recommend to leave it be and get used to the new Unity version. You can get it via the Beta-branch of Rising World on Steam. Its yet pretty basic but the building system is already implemented and way beyond the possibilities of Java-Version.
In Unity you have blocks and shapes too but they all can be resized and positioned as you desire. There is no limitation as what you experience at the moment in Java-version

The Java Version won´t be getting any more updates while Unity will get expanded step by step until its ready to be the official version of Rising World.