Notebooks vs Stacks - expandable and not?

[Leanna 3]

hi, please see the screenshot of my Evernote below - note that: 

1) i shared a note inside 00-IMMEDIATE and from then on the expandable arrow disappeared. Is there a way to get it back? The one shared item has been moved to Communications/Projects  notebook. 

2) I shared Communications/Projects notebook and when the arrow disappeared I thought ok let me just make a stack (00-COMMUNIC/PROJ) but I'm unable to move the notes out of the notebook Communications/Projects into the stack. Please help me either get the expandable arrow back on Communications/Projects notebook, then I will just delete the stack... I realize these are probably dumb questions but I can't find answers so creating this thread...  TRULY APPRECIATE your help!

[DTLow 5,736]

A correction to the terminology
- Notes are stored in a Notebook
  Notes are not stored in a Stack
- Notebooks are grouped in a Stack (Optional)
  The stack shows the "expandable arrow" to show/hide the group notebooks

You do not share a note into a notebook. 
A note is assigned to a notebook or put into a notebook.
A notebook is assgned to a stack or put into a stack.

What device/platform are you using?

Your screenshot shows
     Stacks           Notebooks                           Notes

🔽 00-COMMUNIC/PROJ 
                          Communications/Projec...         6

       (none)       00-IMMEDIATE                           16
       (none)       01-PROJECTS IN S ASIA             1

🔽 ADMIN        Admin                                         30
                           Discipleship                                 2
                           SAsia                                          32

[Leanna 3]

Thank you DT Low for weighing in! I'm on a PC running Win 10. 

To clarify: First I shared a NOTE residing inside Notebook 00-IMMEDIATE with my colleague (share-input her email addr - gave her permission to edit)

Then I realized I needed to share more notes with her and decieded to put them into one new NOTEBOOK and share the whole notebook with her. so I created  Communications/Projec... notebook and shared it with her, but in neither 00-IMMEDIATE nor in  Communications/Projec... the expandable arrow disappeared as soon as the notebook inside it (00-IMMEDIATE) and the notebook ( Communications/Projec...) was shared. 

How can I get the expandable arrow back?  

[DTLow 5,736]

3 hours ago, Leanna said:

the expandable arrow disappeared as soon as the notebook inside it (00-IMMEDIATE) and the notebook ( Communications/Projec...) was shared.

afaik    Sharing notebooks has no impact on Stack organization (expandable arrow)

However, a Stack only exists while it contains Notebooks
Remove the Notebooks, the Stack disappears.

>>How can I get the expandable arrow back?  

Create a new stack with notebooks.

[Leanna 3]

ok I finally figured out the expandable arrow only pertains to stacks and the individual notes inside the notebooks arent actually expandable to be viewed in the left column. Thank you. 

[DTLow 5,736]

1 hour ago, Leanna said:

ok I finally figured out the expandable arrow only pertains to stacks and the individual notes inside the notebooks arent actually expandable to be viewed in the left column. Thank you. 

Right, In tne three panel display, the notes are listed in the center panel
Notebooks are listed in the left panel (sidebar)
Notebooks can be grouped into Stacks (expandable)