After re opening a file chapters are gone

[dagolinuxoid]

The script provides creation of chapter marks by pressing Shift + c. However after closing the file and opening it again there are no chapters. I've tried Shift + b combination to save but it looks like it doesn't work ( There is no global keyboard shortcut conflict there - as I've reassigned the binding to other combination and get the same result ). Where it suppose to save these xml files and it should be os notification upon doing so? Any ideas?

[dagolinuxoid]

Some output

[createchapter]
[createchapter] stack traceback:
[createchapter] 	mp.defaults:230: in function 'fn'
[createchapter] 	mp.defaults:65: in function 'handler'
[createchapter] 	mp.defaults:380: in function 'handler'
[createchapter] 	mp.defaults:510: in function 'call_event_handlers'
[createchapter] 	mp.defaults:552: in function 'dispatch_events'
[createchapter] 	mp.defaults:503: in function <mp.defaults:502>
[createchapter] 	[C]: at 0x55e7711e6780
[createchapter] 	[C]: at 0x55e7711e6f30
[createchapter] Lua error: /home/ah/.config/mpv/scripts/createchapter.lua:73: attempt to concatenate local 'euid' (a nil value)

[VoidVampire]

I was having same issue on my Fedora 39, with flatpak mpv.
I fixed it by using this command in terminal: flatpak override --user --filesystem=home io.mpv.Mpv