I have a vague recollection of seeing somewhere in Help (or whatever it's called) a comment that you can have only one attempt at making the recovery discs. After that I think that you have to buy a set from Sony. I have another vague recollection that I nearly fell foul of this but fortunately had not started the process so was OK. I might be confusing this with my other (HP) computer, though. I think that the best idea is to contact Sony support.
OnePlus 5T review: Hands-on