I have good news. I have managed to found and fix this bug. However, since the bug is in the main updater application (which is problematic to update), I prefer to wait until we release a 1.8.0 RC2 version in a couple of days.
Thank you for your patience and support. For now, you can apply the workaround consisting of manually removing the "updates.xri" file, as I explained above. Anyway, this is a matter of a couple of days, as I have said. I hope RC2 will be fully stable and free from all of these nuisances.
Happy New Year to everybody!