With 110 nights* in 2018 i was granted Plat Premier + Ambassador.
This is likely a bug which i hope would be sorted out soon given that my spend was no where near 20,000.
*Fun fact: All nights were from rewarding events.
Update.
Looks like Marriott patched it. They downgraded my status to Plat Premier (without Ambassador)
The option to combine accounts came up i'll update again if i qualified for any 50 or 75 gifts.