Comment 1 for bug 1843629

Following the upgrade RP4 from stetch to buster.
testfile "im1.m"

clear
%close all
I = imread("thumb0000.bmp");
figure;
imagesc(I);
colormap 'gray'
colorbar;
grid;

Octave fails to plot
On the raspbian IRC it was recommended to try with LIBGL_ALWAYS_SOFTWARE=true
This did not help.
I posted on octave IRC and was told that this was a raspbian bug.

GNU Octave - Bugs: PMbug #56570, unable to plot with OpenGL on... [Savannah]

LIBGL_ALWAYS_SOFTWARE=true octave
GNU Octave, version 4.4.1
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octave:1> ls *.bmp
r1thumb0000.bmp r4thumb0000.bmp t250thumb.bmp t300thumb.bmp tt.bmp
r2thumb0000.bmp r5thumb0000.bmp t260thumb.bmp thumb0000.bmp
r3thumb0000.bmp r6thumb0000.bmp t275thumb.bmp thumb.bmp
octave:2> im1
warning: opengl_renderer: Error 'invalid enumerant' (1280) occurred in init_gl_context
warning: called from
    allchild at line 40 column 7
    newplot at line 202 column 11
    image at line 113 column 11
    imagesc at line 98 column 12
    im1 at line 5 column 1
warning: opengl_renderer: Error 'invalid operation' (1282) occurred drawing 'text' object
warning: called from
    allchild at line 40 column 7
    newplot at line 202 column 11
    image at line 113 column 11
    imagesc at line 98 column 12
    im1 at line 5 column 1
warning: opengl_renderer: Error 'invalid enumerant' (1280) occurred in init_gl_context
warning: called from
    newplot at line 203 column 11
    image at line 113 column 11
    imagesc at line 98 column 12
    im1 at line 5 column 1
warning: opengl_renderer: Error 'invalid operation' (1282) occurred drawing 'text' object
warning: called from
    newplot at line 203 column 11
    image at line 113 column 11
    imagesc at line 98 column 12
    im1 at line 5 column 1
octave:3> warning: opengl_renderer: Error 'invalid enumerant' (1280) occurred in init_gl_context
warning: opengl_renderer: Error 'invalid operation' (1282) occurred drawing 'text' object
warning: opengl_renderer: Error 'invalid operation' (1282) occurred drawing 'image' object
warning: opengl_renderer: Error 'invalid enumerant' (1280) occurred drawing 'axes' object
warning: opengl_renderer: Error 'invalid operation' (1282) occurred drawing 'text' object
warning: opengl_renderer: Error 'invalid operation' (1282) occurred drawing 'image' object
warning: opengl_renderer: Error 'invalid enumerant' (1280) occurred drawing 'axes' object
warning: opengl_renderer: Error 'invalid enumerant' (1280) occurred in init_gl_context
warning: opengl_renderer: Error 'invalid operation' (1282) occurred drawing 'text' object
warning: opengl_renderer: Error 'invalid operation' (1282) occurred drawing 'image' object
warning: opengl_renderer: Error 'invalid enumerant' (1280) occurred drawing 'axes' object
warning: opengl_renderer: Error 'invalid operation' (1282) occurred drawing 'text' object
warning: opengl_renderer: Error 'invalid operation' (1282) occurred drawing 'image' object
warning: opengl_renderer: Error 'invalid enumerant' (1280) occurred drawing 'axes' object

Thanks in advance Let me know if I can provide any additional information.