Mod is crashing when opening the window, both with the shorcut bar and Ctrl-Alt-,
Error message at the end.

I don't know how long it's been crashing because I don't open it often. It's crashing in all 3 autosaves (45 minutes), and it's crashing if I go back to 1.0.9 version.
I have SE+Power Armor MK3 mods, and a bunch of other mods that don't show any other milesntone. 300+ hours.

It is NOT crashing on a new game with all the same mods : https://i.imgur.com/L7P3GmA.png

I made a fork of my save, deactivated then reactivated Milestones, but it lost all my times : https://i.imgur.com/lNdz5Wz.png

Error message :

The mod Milestones (1.0.10) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Milestones::milestones_toggle_gui (ID 213)
Gui element with name milestones_display_scroll already present in the parent element.
stack traceback:
[C]: in function 'add'
Milestones/scripts/gui_display_page.lua:135: in function 'build_display_page'
Milestones/scripts/gui.lua:114: in function 'open_gui'
Milestones/scripts/gui.lua:145: in function 'toggle_gui'
Milestones/scripts/gui.lua:208: in function <Milestones/scripts/gui.lua:206>

I won't be able to take a look at this this weekend unfortunately. Could you upload and send me a copy of a faulty save?

Also try this command and see if it fixes anything: /c remote.call("milestones", "reinitialize_global") (This is considered a cheat-mode command so it will disable your achievements unfortunately.)

Command seems to have worked, I can open the panel without crashing and it kept my times.
Don't really care about achievements anyway with all these mods.

Crashing save is available here (102MB) https://drive.google.com/file/d/1-K23a04VAg_zug9xUvgLGfUPjZV9Ms4d/view?usp=sharing

Though I don't understand yet how your save file ended up in that state, I modified things in 1.1.0 so that the mod will not crash even if that state is reached.

Probably too much mod adding/deleting.
It fixed my savegame !
Thank you very much :)