I'm having the EXACT same issue with the hard drive yellow exclamation mark. No matter how many times I clean install, it always appears.
I asked Gabel Aul and he was going to show the Bitlocker team. I thought I was the only person in the world with that problem.
It never appeared in any previous build either.
Right clicking the hard drive shows "Turn Bitlocker On" but it won't work because it displays a message saying it can't save my Recovery key anywhere. When I check Disk Management, it says my hard drive is already Bitlocker Encrypted.
I have looked so far into this issue, from diskpart, to Windows RE/winre.wim to the BCD files and no solution. I have even reinstalled Windows 8.1 from scratch and decrypted the drive using my recovery key from OneDrive.live.com/recoverykey and it still doesn't fix it in Windows 10 (clean install)
If you find a solution, please post it. I am hoping its just an icon bug with 10074, because like I said before, the drive is already encrypted in disk management and working fine, and no other previous build of Windows 10 has had this issue for me.