Como fazer o Ubuntu MATE 21.04 lembrar do meu aplicativo padrão para arquivos .desktop no menu de contexto?

Sistema: Ubuntu Mate 21.04

Desejo que a opção padrão no menu de contexto para edição de arquivos .desktop seja pluma. Mas o MATE se recusa a honrar meus desejos! Como posso dobrá-lo à minha vontade?

Isso mostra a escolha padrão do Libreoffice

Eu escolho "abrir com outro aplicativo" e seleciono pluma. A caixa "lembrar este aplicativo" está marcada.

Mas da próxima vez que eu fizer isso, o Libreoffice ainda será o padrão.

Como tornar plumao item de menu de contexto padrão para editar arquivos .desktop?

Por solicitação, aqui está ~/.config/mimeapps.list:

[Default Applications]
x-scheme-handler/http=firefox.desktop
x-scheme-handler/https=firefox.desktop
text/html=firefox.desktop
x-scheme-handler/about=firefox.desktop
x-scheme-handler/mailto=thunderbird.desktop
application/x-extension-eml=thunderbird.desktop
message/rfc822=thunderbird.desktop
inode/directory=caja-folder-handler.desktop
text/plain=pluma.desktop
audio/mpeg=rhythmbox.desktop
audio/x-mpegurl=rhythmbox.desktop
audio/x-scpls=rhythmbox.desktop
audio/x-vorbis+ogg=rhythmbox.desktop
audio/x-wav=rhythmbox.desktop
video/mp4=io.github.celluloid_player.Celluloid.desktop
video/mpeg=io.github.celluloid_player.Celluloid.desktop
video/mp2t=io.github.celluloid_player.Celluloid.desktop
video/msvideo=io.github.celluloid_player.Celluloid.desktop
video/quicktime=io.github.celluloid_player.Celluloid.desktop
video/webm=io.github.celluloid_player.Celluloid.desktop
video/x-avi=io.github.celluloid_player.Celluloid.desktop
video/x-flv=io.github.celluloid_player.Celluloid.desktop
video/x-matroska=io.github.celluloid_player.Celluloid.desktop
video/x-mpeg=io.github.celluloid_player.Celluloid.desktop
video/x-ogm+ogg=io.github.celluloid_player.Celluloid.desktop
image/bmp=eom.desktop
image/gif=eom.desktop
image/jpeg=eom.desktop
image/png=eom.desktop
image/tiff=eom.desktop
application/pdf=atril.desktop
application/vnd.oasis.opendocument.text=libreoffice-writer.desktop
application/msword=libreoffice-writer.desktop
application/vnd.openxmlformats-officedocument.wordprocessingml.document=libreoffice-writer.desktop
application/vnd.oasis.opendocument.spreadsheet=libreoffice-calc.desktop
application/vnd.ms-excel=libreoffice-calc.desktop
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet=libreoffice-calc.desktop
application/x-desktop=pluma.desktop
application/rtf=libreoffice-writer.desktop
application/x-shellscript=pluma.desktop

[Added Associations]
audio/mpeg=vlc.desktop;rhythmbox.desktop;
audio/x-mpegurl=vlc.desktop;rhythmbox.desktop;
audio/x-scpls=vlc.desktop;rhythmbox.desktop;
audio/x-vorbis+ogg=vlc.desktop;rhythmbox.desktop;
audio/x-wav=vlc.desktop;rhythmbox.desktop;
video/mp4=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
video/mpeg=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
video/mp2t=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
video/msvideo=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
video/quicktime=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
video/webm=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
video/x-avi=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
video/x-flv=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
video/x-matroska=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
video/x-mpeg=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
video/x-ogm+ogg=vlc.desktop;io.github.celluloid_player.Celluloid.desktop;
application/rtf=libreoffice-writer.desktop;

@ninguém em um comentário sugeriu que eu tentasse a entrada Propriedades no menu de contexto. Aqui é onde realmente fica estranho. Para começar, parecia assim.

Eu pensei que a vitória estava ao meu alcance! Eu deletei o Libreoffice e a caixa ao lado do Pluma foi marcada. Com certeza isso funcionaria! Mas NÃO , rejeição, agora o menu de contexto não tem padrão, só mostra Abrir com outro aplicativo Neste ponto estou começando a pensar que alguém não quer que eu abra estes com o Pluma!