Walls that were transferred from world do not render properly

This bug feeds my hope one day see vertical slabs in Minecraft. Because? Because when I transferred my construction, which had walls in the composition, they seemed to announce a future new rotation for the existing slabs. I've already reported this bug several versions ago, but it doesn't seem to have been fixed or perhaps reappeared.

How I got to this:

 

_1. First, I went to the Play Store and downloaded this app:https://play.google.com/store/apps/details?id=com.electricfoal.buildingsformcpe;_

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 2. Then I downloaded this other app (https://play.google.com/store/apps/details?id=com.lyxoto.master.forminecraftpe) and downloaded the map New Clark City 2.0;

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 3. Then I used the Building for Minecraft app to copy my build from one world to another. The build came all broken but I believe this is a problem with the app, not Minecraft;

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 4. Then, I entered this map already with this constructionz I went to the construction site that I copied, when I noticed that the walls had the problem shown in the video.

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 I REALLY hope I helped.