PDF comments panel does not stick in workspace
We have discovered that the PDF Comments panel disappears when a document is closed.
But we have also found that any panels that are grouped with the PDF Comments panel in a saved workspace disappear when the document is closed.
Refreshing the workspace brings them all back.
Thanks for reporting this issue. We have started work on fixing it.
Adobe InDesign team
I've noticed that too; thanks for working on it. Interesting, that only so few people noticed it...