Eric S Fraga <e.fraga@ucl.ac.uk> writes:

> Just to say that RET seems to be working again.  No idea what happened
> or changed, mind you...  Sorry for the noise.

Glad things fell back in place somehow.  The only explanation I can
conjure for weird/transient/irreproducible behaviour is directory-local
settings, e.g. org-mode.git's .dir-locals.el sets org-adapt-indentation
to nil… but there might have been something else at work in your case 🤷