@maxwinkens First time using AutoCAD if I may ask? Welcome.

As explained in HELP in your AutoCAD, DIVIDE command does not break line/plines, never has, probably never will: all if does is place points (or if you chose, other objects) at equally spaced distances

And PEDIT only does the following (also from HELP):

If you re looking for ways in the program to break lines and Plines into segments, you will need to use the command BREAK https://help.autodesk.com/view/ACDMAC/2023/ENU/?guid=GUID-7F63FF08-BF72-4975-8AFA-B6B3DC058F35

if you are using AutoCAD, an not LT version of AutoCAD, there may be LISP options to customize to your need too.

HTH