Bug in the LibreOffice graphical interface

Description:
I recently accessed LibreOffice (LO) on Lubuntu 20.10. Often - if not always - either when creating a new document or editing an existing one, when inserting formulas, when inserting OLE Objects, when inserting frames, or even, in some cases, as soon as the LO starts, the LibreOffice window is unconfigured and makes using the program somewhat impossible; again, it always happens.

As I had already contacted a support through the link “https://ask.libreoffice.org”, in “https://ask.libreoffice.org/en/question/276821/bug-in-the-libreoffice-graphical-interface/”, I discovered that the probable cause of the error was in the package “libreoffice-qt5”, which apparently was in conflict with some other package.

The implemented solution was to exclude the package “libreoffice-qt5”, and this solved the problem; graphical flaws did not appear again after this action.

In fact, I had both installed LibreOffice through the Lubuntu repository and the official website, and the error was present in both;

Note: the pc is newly formatted, so there are no significant changes in the system settings, in order to affect the LO;

Steps to Reproduce:

  1. insert a formula (which will open the formula editor)
    (OR insert a frame,
    OR insert a OLE Object);
  2. exit the formula editor and go back to the text editor
    (no need to type anything in the formula);

Actual Results:
At this point, the error must have already occurred, and the LibreOffice window is already strangely corrupted, with parts of the image locked, another part darkened, and so on;

Expected Results:
Ideally, the LO window should not corrupt; in fact, if you go to other software in the suite without ending the session, this failure will accompany all other programs;

Reproducible: Always

User Profile Reset: Yes

Bug images in the LibreOffice window:
screen4

Additional Info:
Here is information extracted from the LO help menu:

Version: 7.0.2.2
Build ID: 00(Build:2)
CPU threads: 4; OS: Linux 5.8; UI render: default; VCL: gtk3
Locale: pt-BR (pt_BR.UTF-8); UI: en-US
Ubuntu package version: 1:7.0.2-0ubuntu1
Calc: threaded

Note that it may be important:
I checked LibreOffice (LO) version 6.3.5.2 - which is on another laptop, with Lubuntu 19.10 - and confirmed that this “libreoffice-qt5” package was not present in that version (which is without this error); on the other hand, the package “libreoffice-jdk3” already accompanied the previous version;

With Lubuntu 20.04.1 and LibreOffice 6.4.6.2 I had a similar issue with Calc and Writer in two different computers. I never used OLE Objects, but often my toolbar icons disappered, specially when I used border icons. If I resized the windows the toolbar icons returned.

I unistalled every libreoffice’s package and reinstalled with sudo apt install libreoffice libreoffice-l10n-it libreoffice-help-it --yes (I’m Italian) and everythings works fine.

I’ve read your message and I noticed that the package “libreoffice-qt5” was present in the first installation of Lubuntu, but not now.