Text disappears when decreasing size

[thomasashleeee]

I have a 500+ page doc in Indesign with flowing text. Selected all, tried to decrease the size by one pt and the first paragraph disappears. Tried cutting and pasting that bit of text after but just removes another, different part. Have updated and restarted but still happens. Any thoughts?

[Peter Spier]

Can we see some before/after screen shots, please.

Also, version of ID and OS.