Impress.
I change the master slide gradient to the colours I want and it loses them upon saving the file.
Why?
Works here.
A hint: I wrote the above as a sample of an “answer” that lacks useful information, just as the question itself. I should had mentioned the version of LibreOffice I used; my OS; and the file format. Also I could provide sample screenshots…
Are you just trying to be awkward or just a prat?
Version: 6.0.7.3
Build ID: 1:6.0.7-0ubuntu0.18.04.10
CPU threads: 2; OS: Linux 4.15; UI render: default; VCL: gtk3;
Locale: en-GB (en_GB.UTF-8); Calc: group