Online display of METAFONT updates incorrectly

[dine2014]

I have installed MikTeX on Windows. When I run mf --interaction=errorstopmode --screen and type the following lines

\relax
showit; fill fullcircle scaled 150; showit;

the following is displayed

and if I start from scratch and type the following lines

\relax
fill fullcircle scaled 80; showit;
unfill fullcircle scaled 40; showit;

only the outer circle is displayed:

But if I sort the edges with

currentpicture:=currentpicture rotated 90 rotated -90; showit;

METAFONT is able to display correctly

Here is my configuration report

Date: 2020-06-21 14:01:36
MiKTeX: 2.9.7440
GitInfo: af89c1b / 2020-05-20 09:20:28
OS: Windows 10 Home China, 64-bit, build 18363
SharedSetup: yes
LinkTargetDirectory: C:\Program Files\MiKTeX 2.9\miktex\bin\x64
PathOkay: yes
LastUpdateCheckAdmin: 2020-06-20 15:29:07
LastUpdateAdmin: 2020-06-20 15:30:50
LastUpdateDbAdmin: 2020-06-20 15:29:04
SystemAdmin: yes
RootPrivileges: no
AdminMode: no
Root0: C:\Users\asus\AppData\Roaming\MiKTeX\2.9
Root1: C:\Users\asus\AppData\Local\MiKTeX\2.9
Root2: C:\ProgramData\MiKTeX\2.9
Root3: C:\Program Files\MiKTeX 2.9
UserInstall: C:\Users\asus\AppData\Roaming\MiKTeX\2.9
UserConfig: C:\Users\asus\AppData\Roaming\MiKTeX\2.9
UserData: C:\Users\asus\AppData\Local\MiKTeX\2.9
CommonInstall: C:\Program Files\MiKTeX 2.9
CommonConfig: C:\ProgramData\MiKTeX\2.9
CommonData: C:\ProgramData\MiKTeX\2.9

And here are my log files: log.zip

• I have read the MiKTeX Contributing Guidelines

[dine2014]

By the way, here is the log file for the first experiment:

This is METAFONT, Version 2.7182818 (MiKTeX 2.9.7440 64-bit) (preloaded base=mf 2020.6.20)  21 JUN 2020 14:12
**\relax

*showit; fill fullcircle scaled 150; showit;
Calling BLANKRECTANGLE(0,500,0,400)
Calling BLANKRECTANGLE(0,500,0,400)

*end

and here is the log file for the second:

This is METAFONT, Version 2.7182818 (MiKTeX 2.9.7440 64-bit) (preloaded base=mf 2020.6.20)  21 JUN 2020 14:14
**\relax

*fill fullcircle scaled 80; showit;
Calling BLANKRECTANGLE(0,500,0,400)
Calling BLANKRECTANGLE(0,500,0,400)

*unfill fullcircle scaled 40; showit;

*currentpicture:=currentpicture rotated 90 rotated -90; showit;
Calling BLANKRECTANGLE(0,500,0,400)

*end