Multiple text selection font-change problem

Howdy!! (← in honor of Minnie Pearl)

STUFF YOU MIGHT NEED TO KNOW:

OS: PCLinuxOS (version 2018.05.12)
GUI: KDE Plasma 5 (version 5.12.5)
LibreOffice: Version: 6.0.3.2
Build ID: 8f48d515416608e3a835360314dac7e47fd0b821
CPU threads: 4; OS: Linux 4.16; UI render: default; VCL: kde4;
Locale: en-US (en_US.UTF-8); Calc: CL

This issue extends across every version of LibreOffice I’ve ever used
on any GNU/Linux-based distro:

When I select multiple words in a document
(using CTRL + DOUBLE-CLICK and/or CTRL + LEFT-CLICK + DRAG),
changing the font family and/or font size and/or font weight of the
selected text will often fail and the text will remain selected until
I close the document and reopen it.

Sometimes this snafu will happen when I’ve only selected a couple
of words in the same paragraph.

Sometimes this snafu will happen when I’ve selected several words
in different paragraphs.

This issue is not a show-stopper for me. I’ve learned to cope with it.
But, I’m curious why it happens and whether the fine folks at LibreOffice
have ever been made aware of it? Or, is this an issue that only occurs on
my computer and only when I am changing the font family, font size, and/or
font weight of several selected words in a document?

(Be aware that I realize that in software functionality, unique circumstances
that apply only to me — and no one else in the entire multiverse — create
problems that no one else has ever experienced.)

[About the OS version designation “PCLinuxOS (version 2018.05)”]

PCLinuxOS is a “rolling release”, so the version designation I
gave it “2018.05.12” is contrived, being made up of the year,
month, and day that I last updated it from the official PCLinuxOS
software repository.

(/me uses Win - so cannot confirm) - but if the problem exist, it’s definitely a bug and should go to bug tracker. Please don’t hesitate to file bugs there.

I use LibO on KDE Plasma too and while I do not experiment your particular problem, I had many problems with this:

UI render: default; VCL: kde4; 

So while I’m waiting for the new Qt5 plug-in (it’s in development), I installed the GTK3 one, uninstalled the old kde4 package and automatically become free of almost any UI problem. Just be careful of selecting a matching widget style for GTK3 apps (Plasma control centre).