I have 5 ram guardians. One of the options is to either replace one of the five I have or to make a brand new guardian. I went to make a new one. The guardian I had went away but I was left with nothing new. The shop took my gems, I got a small amount of astral energy but no new guardian. This was on a fresh playthrough on normal.
You can only have four Guardians of the same type. The “Transmute New Guardian” button doesn’t create a new guardian, it destroys the new Guardian you have received, as the screen you’re on is asking you to replace one of the existing guardians with the new one (destroying the replaced Guardian in the process) or to destroy the new one and keep the other four.
The wording on that is really weird then. Its easy to believe it to be creating a new guardian when in actuality it does the opposite.
Next time you get another Ram guardian look at the two options. One says “Transmute new Guardian” and is referencing the newest received one; the other option says something like “Transmute old/existing Guardian”, and references the highlighted Guardian from your roster.