Mirrors cause my house to glitch

Hi, I haven't seen anybody else discuss this. This has been happening since August or September. Every time I place a mirror into my house, whenever I build or play in live mode in that house other objects outside the house (usually lamps +trees) briefly glitch into the house and flicker out and in over and over again. The only way this doesn't happen is if my camera is angled inside the house w/ all the walls up. I have CC +mods disabled. Why is this happening + how do I fix it? I can't put any mirrors in my homes because the game looks awful.