TWRP: Failed to mount '/preload' (Invalid argument)
I have this problem too, but I can install treble roms, I installed Lineage 17.1 without problems but sometimes I see the message / preload invalid argument, size of partition 0, I am looking for a solution but this error does not disturb my device at all

in xda i encontered this => 
All you need to do is go to official download page, download your official latest rom and flash
Download the most recent firmware and flash in Odin. (There is instructions on how to download the correct firmware in the post)