I have just realized that the align text columns from left to Center, right are as blocks is not working by pressing the Buttons.
I have deselected all Markdown settings disable all plugins up to 'Enhancement' also there I deselect all settings
up to The first 'Enable table formatter in editor' and still could not align Text to the Center are to the right.
I'm on Manjaro and also test the 'joplin-appimage 2.12.19-1' version in a VM with the same issue
If you are using the Rich Text editor, it seems that the alignment configuration for the table does not affect the cells content, but the table location instead. But, as the warning at the bottom shows, the Rich Text editor has a number of limitations, and the create feature is just a way to simplify the table creation for Markdown (Joplin uses Markdown in all notes as far as I know). This worked for me when editing a table using Markdown:
If you need something more complex or different, I think the only option is to use a plugin or maybe an external editor that is capable of adding HTML to the document.