The only time I've ever had this was when the hardware in the system was waiting for a drive to report 'ready' , turns out the drives controller board was faulty and taking it's sweet time returning the signal to the MB.
Maybe your SSHD drive is faulty too ?
One thing I just thought of is maybe a Repair Install might correct or clean up any links to the new 2nd internal disk.
Repair Install Windows 10 with an In-place Upgrade - Windows 10 Forums
I have the same problem on a Z170 motherboard with an NVMe SSD. In searching around for insight, I'm starting to believe that the GPT-UEFI combination is what works best for proper boot behavior from an SSD (especially a fast one like NVMe, but also for SATA like yours). EASUS Partition manager will convert GPT to MBR, and also convert MBR to GPT. I've got Paragon Partition Manager myself, and have sent off a support request to see if my version supports that functionality (my UI doesn't offer it as an option, so I'm probably going to have to "buy up" to their Pro version to make that change). I do plan to get this resolved later this week or over the weekend, and will follow up with what I will learn at that time.
Stay tuned! If I'm right, you may have converted the wrong way (GPT --> MBR, instead of MBR --> GPT). We'll see.
Still running the 2010 custom build here(No UEFI to worry about) while having changed from the Antec 900-1 to 900-2 model case having eSata ports on the front. While I haven't bought an SSD as of yet since the 1tb models are still priced out in orbit somewhere I simply invested in spinners for the capacity.
The flashing dash typically represents the lack of an OS where the bios will search the next drive for a boot loader which is what you are seeing there. I was a little concerned at first with the present build actually one of two when first mixing Sata II with Sata 3 drives and found the two Sata 3 drives were Disk 0 and Disk 1 while the 7 drive being the original host/boot drive was plugged into the first Sata II port. At times with this one on one occasion as well as on past builds having the wrong drive found as the new default would be seen when adding a new drive in if I forgot to get into the bios when going to power up.
The Advanced section in the bios generally has the hard drive list where you may have to recheck to see just which drive by number is at the top which is the default drive under hard drives. You will need to look over that information in the board's user manual. I know that from running not only two separate OS drives but just swapped out the pair of Sata 3 1tb drives for a new pair of Server class 2tb Sata II drives and now where Port #2 is running horizontal not vertical for the 8 S2 ports and pair of S3 ports. I now have to swap cables around a bit to see 10 in Port #1 7 in Port #2 instead of what looks like Port #5 with the first of the two new drives in Port #2 which was thought to be Port #3. The 10 drive being originally the second OS drive used for the 8 CP and Linux was to see the cable swapped with the 7 drive for 10 to be the host/boot.
Once you get familiar with the board itself as far as how things are set up and know your way around in the bios set up this will become second nature in no time. But you need to review the manual for the board you have there.
As for Paragon's software I have been looking at for a period of time now having the Ext5 for Windows in use at the moment while still wanting to get a good look at the Partition Manager.
I got Windows 10 reinstalled on the Z170 Extreme7+ last night, this time making sure to elect UEFI version of the installation media (and using the latest Rufus version (2.7), which permits itself to be designated "GPT Partition scheme for UEFI" in the Partition scheme selection). This produced a new boot drive image that now includes an EFI partition of 100 MB, plus a 450 GB Recovery partition, so I know I've gotten things right this time.
And sure enough, once the motherboard decides to start booting it takes exactly 13-14 seconds to get from the boot screen to the Windows login screen. The only thing is, even though I no longer get a blinking cursor, the machine still sits there with its background screen (Asrock logo) for about 80 seconds before flashing, and then actually starting the boot-up sequence.
I'd still like to figure out why this is happening and get that out of the way, but my problems with the blinking cursor were indeed resolved by switching from MBR to GPT. This goes to confirm my recent reading on the differences between the two disk layouts, chief among which differences is that GPT is more UEFI-friendly.
I had a similar problem a while back and solved it by resetting the CMOS on the motherboard. You might give it a try.
One way to actually see what is going is to simply disable the factory logo and watch as the post screen progresses through each stage before you see the "Loading operating system" displayed as the initial tests finish up. If it's slow where the drives are displayed a drive isn't detected as easily as it should.