This is a user-to-user support forum (i.e. you are not addressing Adobe here).
Bug reports should be sent to: Wishform - Adobe InDesign
By the way, have you tried trashing your InDesign Preferences:
Close and relaunch InDesign, and IMMEDIATELY hold down Ctrl + Alt + Shift (Windows) or Cmd + Ctrl + Opt + Shift (Mac), and respond in the affirmative to the dialog asking if you really want to replace the preferences. you must be extremely fast on the keyboard (if you don’t see the confirmation prompt, you were too slow)
You may have to do it a couple of times before you get the hang of it!
Thank you for your answer.
As I do not have any answer from Adobe for any bug report I made, I share my experience.
I have this bug an a fresh install since the first CC version, maybe before, so it's not coming from the prefs.
I'm a Mac user, maybe someone who uses Windows can respond.
It would be useful to get feedback if the matter is resolved.
I have 4 workspaces on 3 computers. Same problems.
I have another thing.
With another custom workspace, the one for 2 screens with all my panels outside InDesign window, InDesign stay maximize at the opening. But if I un-maximize, I return to the little small window. All panels open at the same position and size and the other screen.
If I open again, I return to the fullscreen with 5 px margin. :-/
I also tried with default workspaces. Same issues.
This seems to be more of a feature request than a bug and this has been the behaviour since long.
I was able to reproduce both the issues too namely the panels getting docked on resizing the window and that the window size is not remembered.
I have requested dp.arno to send another report to Adobe, just in case it gets fixed/looked-up in future releases.