[ESS] Emacs can find R-devel and R-newest, but not R-4.0.x

[Marius Hofert]

Hi,

I used to be able to start a specific R version with M-x R-... but it
doesn't work anymore. On M-x R-<Tab> I see:
R-devel
R-initialize-on-start
R-mode
R-newest
R-transcript-mode
... but no R-4.0.x. I have R-4.0.0, R-4.0.2, R-4.0.3 and R-devel
installed and M-x R-devel and M-x R-newest correctly find and start
R-devel and R-4.0.3, respectively. The other two R versions are set up
exactly in the same way, which is why it's so confusing that they are
not found. Also, in an Emacs shell (M-x shell), R-4.0.<Tab> completes
to all R versions and I can also start every single one of them.

Any ideas what to try?

This is on macOS 10.15.7 with GNU Emacs 26.3 and ESS version 18.10.2
[Released git: d4cd65da6dbf].

Thanks & cheers,
Marius