My props keep getting randomly deleted

As I am building and placing props, the walls just constantly get deleted. I have had this happen before not even just for walls, but floors and other props but this was the time I managed to capture it, I actually capture this bug twice in the same video. I do not not why it happens when I check my memory I am at 15k so no where near the limit so I don’t understand why it does this. Its very frustrating to build an entire floor and/or sctureture only for 95% of it to get deleted. It doesn’t look like a lot gets deleted but prior to the recording I have over 10 rooms just for them to get deleted. Does anyone know why this happens because it makes developing a map essentially impossible.