Hi @Tony Sheppard ,
I did the test as you said. It seems this is not a common issue per my test. After I open the document and save/autosave, the calculated columns show up fine and the [ID] section is not stripped. I did a check out/in test and all was fine as well.
However, we can work together to narrow down and resolve the situation. So, Please kindly provide more information below to let us work further.
1.Are other users with permissions facing the same problem? View through another computer or account.
2.Whether all SharePoint libraries have the same problem? You could create a new SharePoint library to check.
3.Check if the same issue occurs with other SharePoint site collections.
4.You could try to clear browser cache then restart it.
5.Try to use a different browser or your browser's InPrivate mode to see if the same error occurs.
Hope the information can help you. And if there have any unclear or misunderstanding, please feel free to post back and we’ll continue to help you all the time!
Your understanding and patience will be highly appreciated! Hope you have a good day and keep safe!
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