You really should do a Hard Factory Reset when going from Asus to Merlin firmware. See: https://www.asus.com/support/FAQ/1039074/ The AX86U will use Method 2. And double check that the /jffs is mounted after a Hard Reset.
OK.
I'd already hard reset the RT-AC86U and had the issues.
So, TWO brand spanking new AX86U (different model being pointed out here) and a hard reset was done after flashing to Merlin using the Asus Method2.
The issue with NTP not syncing after reboot still exists. Once booted, I have to go into the Administration > System page and press APPLY button then NTP syncs the correct date/time.
On the AX86U's though - I don't have the issue with having to change the login user id just to be able to change any setting on that page.