Question Undo and Redo buttons not working...

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htaccess: Exists | PHP environment: Max execution time: 300 seconds | Max execution memory: 512M | Max file upload: 256M

Kunena menu details:

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ID	Name	Menutype	Link	Path	In trash
489	Foro	kunenamenu	view=home&defaultmenu=490	foro	No
490	Índice	kunenamenu	view=category&layout=list&catid=0	foro/index	No
491	Temas Recientes	kunenamenu	view=topics&mode=replies	foro/recent	No
492	No Leídos	kunenamenu	view=topics&layout=unread	foro/unread	No
494	No Replies	kunenamenu	view=topics&mode=noreplies	foro/noreplies	No
495	Mis Temas	kunenamenu	view=topics&layout=user&mode=default	foro/mylatest	No
496	Perfil	kunenamenu	view=user	foro/profile	No
493	Crear Tema	kunenamenu	view=topic&layout=create	foro/newtopic	No
497	Help	kunenamenu	view=misc	foro/help	No
498	Buscar	kunenamenu	view=search	foro/search	No
499	Foro	mainmenu	Itemid=489	foro-2020	No

Joomla default template details : Favourite | author: FavThemes | version: 3.3 | creationdate: September 2012

Kunena default template details : Crypsis | author: Kunena Team | version: 5.2.2 | creationdate: 2021-01-13

Kunena template params:

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DefaultCategoryicon
profileIconset	default
DefaultIconset	default
editorIconset	default
bootstrap	1
icomoon	1
tooltips	1
borderless	1
SubjectLengthMessage	80
fullactions	1
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displayMenu	1
displayDropdownMenu	0
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displayAnnouncement	1
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avatarPosition	left
avatarType	none
labels	0
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topicicontype	fa
fontawesome	0
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socialsharetag
socialtheme	classic
optional_username	0
writeaccess	0
localstorage	0
IconColor	#006600
IconColorNew	#006600
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Underline	1
Strike	1
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BulletedList	1
NumberedList	1
Blockquote	1
JustifyLeft	1
JustifyCenter	1
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JustifyBlock	1
Link_Unlink	1
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Code	1
Ebay	1
Twitter	1
Instagram	1
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TextColor	1
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Map	1
Video	1
editorButtons
nameskinckeditor
avatarSizeX	40
avatarSizeY	90
avatarSizeXThumb	36
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avatarSizeYList	36
avatarSizeXPost	144
avatarSizeYPost	144
avatarSizeXProfile	200
avatarSizeYProfile	200
templatebyText
templatebyName
templatebyLink

Kunena version detailed: Kunena 5.2.2 | 2021-01-13 [ Iris ]
        | Kunena detailed configuration:

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Kunena config settings:
board_offline	0
enablerss	0
threads_per_page	20
messages_per_page	10
messages_per_page_search	15
showhistory	1
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template	crypsis
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imagesize	5550
filetypes	txt,rtf,pdf,zip,tar.gz,tgz,tar.bz2
filesize	120
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minimal_user_posts_add_url_image	10

| Kunena integration settings:

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Kunena - Finder Disabled
 Kunena - AltaUserPoints Disabled
 Kunena - Community Builder Disabled
 Kunena - Easyblog Disabled
 Kunena - Easyprofile Disabled
 Kunena - Easysocial Disabled
 Kunena - Gravatar Disabled
 Kunena - JomSocial Disabled
 Kunena - Joomla Enabled:  access=1  login=1  
 Kunena - Kunena Enabled:  avatar=1  profile=1  
 Kunena - UddeIM Disabled

| Joomla! detailed language files installed:

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Joomla! languages installed:
es-ES	Spanish (español)
en-GB	English (United Kingdom)

Third-party components: None

Third-party SEF components: None

Plugins: None

Modules: None

For some reason the undo and redo buttons are not working after the Kunena 5.2.2 upgrade and ctrl+z is also not working.

Any ideas?

Have you tried it here? I can't reproduce this problem. Tested with Chromium, Firefox and Opera.

yes, I have tried it here, and it works fine. However, on my site the undo and redo buttons are "disabled" for some reason. It must be a problem with my site, then, but if you have any ideas of what could be the issue and how to fix it, I would appreciate it.

It is difficult to find the cause if the error does not occur generally, it can be anything. Have you edited the CKEditor configuration file?
Maybe it helps if you install Kunena again over it.