I have SSHD Seagate Drives on 3 computers all I7 and GeForce video cards
They have a 8 gig cache in them and after a few restarts my system restarts in 30-40 seconds instead of 3-4 minutes since the Fall creators update every time I get an update like Office or windows 10 or even if I add a movie or small game it kills the cache in the SSHD Drive and I have to restart the system 8 to 10 times to refill the cache in the drive o it will restart in 30-40 seconds sometimes this is twice a day.
I think they want all of us to buy SSD drives but who can afford to buy a few 1T SSD drives
Unfortunately, this is an inherent flaw with SSHD. It is always going to be a juggling act trying to get the things you want into the solid state portion of the drive, especially after large updates which involve a lot of disk access. The same problem would apply to any modern operating system where the installation size is larger than the solid state cache.
128 and 256 GB SSDs are relatively cheap now, so a better option is to have one of these for your operating system and applications and a separate, larger storage drive (like your 1TB SSHD) for your data.