Description:
I have a numbered list spread out over multiple slides. I do this by creating a new list starting with the number after the last point on the previous slide.

It allows me to input a number, but it doesn't actually change the number. Reopening Bullets and Numbering after clicking OK once again shows the old number. 

I CAN change the number by clicking the up and down arrow buttons.

Steps to Reproduce:
1. Create a slide with Content
2.Instead of bullets in the contents box, choose any numbering system (1,2,3 / i,ii,iii etc)
3.Input any number >1 in the box "Start at"
4. Click OK.

Actual Results:
The number still starts at 1 (or i or I or a, etc).

Expected Results:
It should start from the number inputted.


Reproducible: Always


User Profile Reset: Yes


OpenGL enabled: Yes

Additional Info:
OS: Ubuntu 20.04 (64 bit)
LO Version: 6.4.3.2
Build ID: 1:6.4.3-0ubuntu0.20.04.1
CPU threads: 8; OS: Linux 5.4; UI render: default; VCL: gtk3; 
Locale: en-GB (en_GB.UTF-8); UI-Language: en-US
Calc: threaded