Can you please share screenshot for this issue. And , are you facing this issue for all the documents ?
Thank you for your patience all this while. The fix of the issue is now part of InDesign’s latest update, Id 13.1
Update your InDesign through Creative Cloud app to Id 13.1
AbhinavRijali Cahyo Wicaksono commented
Panel Swatches (didnt show button create swatch etc). Master Page empty, Panel Page not full display