Hi,
I've been using joplin for quite some time and I always had both text editor and a kind of WYSIWG visualization. I don't see anymore the text editor and I couldn't find were I return to the old configuration. I just can see the WYSIWG version of the editor.
I can see that editor.codeView is set to false in settings.json but I can't find were I could switch that in the graphical interface.
I just did the manual correction in settings.json settings.json and seems to be ok. Now, I can switch between only WYSIWG mode and the mode that combines both WYSIWG and editor codeview.