Intermittent success with embedding posts

I am having a maddening problem with my web site – Please help. I can sometimes embed posts from Twitter and Instagram but it’s so hit or miss – I have no idea what will post and what won’t until I try and either succees or fail. Instagram always gives me the option to embed so I copy the embed code but for some reason it’s about a 50/50 chance it will post – no matter if I keep trying. Youtube embeds work all the time but Twitter and Instagram for whatever reason are haphazard. Thank you for any guidance.

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