@CYB
I know what @Raymon7n wrote sounds (reads) weird, but have come to a somehow similar solution if I understood well what he wrote. So, here it is, try it before you reply it’s not related. It’s weird, but it works:
I had created a BP solution, and when I came to create a plugin, I was left with the only solution to create a “Content plugin” :/.
I then proceed as @Raymon7n suggested. I created a dummy C++ class, was then ask to quit the editor, compile the project with visual to launch the editor. Then went back to plugins creation to find out that all of a sudden, a lot of kind of plugins have appeared, including library, third party, … This operation unlocked hidden plugins type. Please, don’t tell us it’s weird or unrelated. I know it’s weird, but it works. I think @Raymon7n did not bother explain in details because obvously you didn’t even try.
So, I’m telling for those who are looking to find a solution and willing to try: It worked for me - Try it