Description:
In a simple sheet (example attached) with autofiltered columns, artefacts will appear in A1 when the autofilter tags are selected.
They are present even if the cell is populated but disappear when A1 is focused.
They will also disappear after an indeterminate period of time has elapsed.
They can behave slightly differently depending upon whether the filter headers are on the same row(1) or the next row(2).
Also, the location of the artefact within A1 is relative to the column for the selected filter(s)
Posting to AskLO "Strange Artefacts" has elicited the information that it is also "Reproducible with:-
    LO 5.4.7
    LO 6.4.7
    LO 7.0.6
    LO 7.1.6
    LO 7.2.1
WIN10"




Steps to Reproduce:
From the attached sheet select the autofilter tag and observe the contents of A1.
Continue selecting autofilter tags to create more artefacts NOTE: it's necessary to deselect the last used tag by clicking anything once prior to the next selection

Actual Results:
Artefacts appear in A1 which appear to indicate the column of the autofilter selected

Expected Results:
Production of the appropriate dropdown and only the dropdown


Reproducible: Always


User Profile Reset: Yes


OpenGL enabled: Yes

Additional Info:
Version: 7.2.1.2 (x64) / LibreOffice Community
Build ID: 87b77fad49947c1441b67c559c339af8f3517e22
CPU threads: 4; OS: Windows 10.0 Build 19042; UI render: Skia/Raster; VCL: win
Locale: sv-SE (en_GB); UI: en-GB
Calc: threaded