emacs starts writing in reverse order

[Luca Ferrari]

Hi all,
not sure what the problem is, but using packaged emacs 26.3
(ubuntu/neon), spacemacs 0.300, I have a problem editing org mode
source code snippets: whenever I start a src code block, the editing
switches to an inderect buffer, but when I exit from the buffer to the
original document Emacs starts writing in the opposite direction.
I mean that the cursosr is fixed on the left of the line, and words
are typing in an append mode, so that "emacs" appears as "scame". This
happens only in the current buffer, other buffers do behave correctly.
What is happening? I suspect is something related to bidirectional
editing, could it be?

Thanks,
Luca