Locale update fails on sanity checks

The problem I've found is very similar to what reported and apparently not resolved with https://github.com/decidim/decidim/issues/3983. When I try to update the locales the snaity checks fail during the verification. The same error happens in dev and prod environment with recommended configuration in your guide (Ubuntu 18.04, ruby 2.5.1 and decidim 0.17.0), of course no locales are updated. Can you please help? Thanks, Gian Luca