I'm currently Titanium (Plat Premier in 2018) and was expecting to be Platinum - either from my 25 qualifying SPG stays last year or from the soft landing.
Having checked my LPT stats, it seems that my Platinum qualification for 2018 has now been recognised. I haven't yet combined my accounts, however, as I was too worried about doing that until the SPG qualification route was confirmed. Somehow I get the feeling that the only reason I still have Titanium is because I never combined the accounts.