Thank you for reporting the bug.
Could you please try to reproduce it with a master build from http://dev-builds.libreoffice.org/daily/master/ ?
You can install it alongside the standard version.
I have set the bug's status to 'NEEDINFO'. Please change it back to 'UNCONFIRMED' if the bug is still present in the master build

I would not know which RPM file could be suitable for my system, since files' name sare partially not self-explicit, neither to which directory it should be best to install and how to remove it once installed. I guessed Appimmages that I used to use for testing purpose would suit once more well if only they were available.

(In reply to ricky.tigg from comment #2)
> I would not know which RPM file could be suitable for my system, since
> files' name sare partially not self-explicit, neither to which directory it
> should be best to install and how to remove it once installed. I guessed
> Appimmages that I used to use for testing purpose would suit once more well
> if only they were available.

Since you reported this issue against 6.4 alpha1. could you please try with beta1 from http://libreoffice.soluzioniopen.com/index.php/6-4/

Here it was, http://libreoffice.soluzioniopen.com/index.php/daily-version/.

Version: 6.4.0.0.alpha1+; Build ID: 80109586e6cb6d3e2e0a53a9079c3125ec9b8368; CPU threads: 2; OS: Linux 5.3; UI render: default; VCL: gtk3; TinderBox: Linux-rpm_deb-x86_64@86-TDF, Branch:master, Time: 2019-11-01_23:56:52
Locale: fi-FI (fi_FI.UTF-8); UI-Language: en-US; Calc: threaded

Not reproducible.

Created attachment 156506 [details]
Navigator's size reduced according to vertical axis – All categories empty

One new condition found; Navigator's size to be reduced according to vertical axis while leaving all categories empty.

Current comment obsoletes previous one. Note that here mentioned Navigator's size expansions and reductions are meant according to vertical axis.

Conditions:
When Navigator's categories containing at least one element are all collapsed, and Navigator's size is reduced beyond category Drawing objects, vertical scroll-bar is no longer visible.

Steps:
1. While in Navigator's all categories are fully visible with space for an up to come element, produce a single element under a single category; e.g Headings category;
2. Expand Headings;
3. Reduce Navigator's size beyond category Comments;
4. Collapse Headings;
5. Expand Navigator's size beyond category Drawing objects;
6. Reduce Navigator's size beyond category Drawing objects.

Results regards to vertical scroll-bar – Note: Results from 1. to 5. are expected:
1. and 2. – not visible 
3. and 4. – visible
5. – not visible
6. – no longer visible (unexpected)

I can't confirm it with

Version: 6.5.0.0.alpha0+ (x64)
Build ID: 350d25da375f221edfa37309324ce3c68cf297ef
CPU threads: 4; OS: Windows 10.0 Build 18362; UI render: default; VCL: win; 
Locale: de-DE (de_DE); UI-Language: en-GB
Calc: threaded

I assume, your bug is about floating window of navigator. Is it perhaps possible to add a screencast? Perhaps it's easier then to reproduce the bug.

Created attachment 157318 [details]
Queried material

I confirm it with the floating navigator window, following the steps, that are shown in the screencast

Version: 7.0.0.0.alpha0+ (x64)
Build ID: 5dcbd1bb557450a2d658a710c163b310c0cee157
CPU threads: 4; OS: Windows 10.0 Build 18363; UI render: Skia/Raster; VCL: win; 
Locale: de-DE (de_DE); UI-Language: en-GB
Calc: CL

Same in

Version: 6.3.5.2 (x64)
Build-ID: dd0751754f11728f69b42ee2af66670068624673
CPU-Threads: 4; BS: Windows 10.0; UI-Render: Standard; VCL: win; 
Gebietsschema: de-DE (de_DE); UI-Sprache: de-DE
Calc: threaded

Additional information: The general behaviour seems to be, that scroll bar is always disabled, if all elements are empty or collapsed.

Jim, I'm sure you can give some informations about it?

(In reply to Dieter from comment #11)
> I confirm it with the floating navigator window, following the steps, that
> are shown in the screencast

> Jim, I'm sure you can give some informations about it?

Dieter, thanks for the confidence!

I repro with sidebar floating navigator when the window is made smaller than the toolbox horizontal size. When I size the window horizontally to reveal all items in the toolbox I see the content view vertical scroll bar. 

I don't repro with F5 navigator. It doesn't allow making the window horizontally smaller than the toolbox.

(In reply to Jim Raykowski from comment #12)
> I don't repro with F5 navigator. It doesn't allow making the window
> horizontally smaller than the toolbox.

So this is the desired result also for the floating window?

In v. 7.4.5.1, in respect to that vertical bar i can observe advanced behaviours which are: bar full exhibition as well as full disappearance are progressive while the screen pointer is in motion respectively towards the bar, and either away from it or while being motionless. At the time i reported i did not investigate whether the original version could integrate those features. For a non-member of the developer team, unknown are the intended behaviours. That at least remained.