My guess is that this happens because you opened — in other words converted — a file created in an earlier version of InDesign, so you have to resave it.
Is the file from a previous version?
When you open a file saved by a previous version, the file is
converted, and is the same as a new file until saved.
Kasyan beat me to it!
You are right.
Thanks for your help.
but only Kasyan gets points,
1 person found this helpful
I'd say it was at least helpful!