A first shortcut key operation on a multiple cells' selection works properly.
However, any subsequent operation impacts only the top row of the selection.
It can be observed when using CTRL+SHIFT+I, CTRL+SHIFT+D, but also ALT+Up/ALT+Down.

Environment
Python 3.10.12
wxPython 4.2.1
robotframework 6.0.2
robotframework-ride 2.1.dev53
Ubuntu 22.04.4 LTS

Steps

1. Select multiple cells
   
2. Press shortcut CTRL+SHIFT+I to insert cells. (OK)
   
3. Press CTRL+SHIFT+I again. The action only occurred on the top row of the selection.
   
4. Select multiple cells again. (refresh selection)
5. Press shortcut CTRL+SHIFT+D to remove multiple cells. (OK)
   
6. Press shortcut CTRL+SHIFT+I to insert cells. The action only occurred on the top row of the selection.
   

ALT+Up scenario:

1. Select cells
   
2. Press ALT+Up (OK)
   
3. Press ALT+Up again. Only "4th line" moved up.
   

Additional info
It looks like an active selection persist in cache only for one action.

*** Test Cases ***
Test Rows
    Log    1st line
    Log    2nd line
    Log    3rd line
    Log    4th line