I’d just like to add that I haven’t had any problems using BDO or BPI machines when I’ve been in Makati and other areas of Metro Manila.
Like other users I just make sure I enable the mag stripe feature each day.
These machines will ask you if you want to withdraw money from your Checking, Savings or Loan account. When I’ve used my NatWest debit card in the past, only Savings worked so I always select Savings when I use my Monzo card. I’m not sure if the other options work with the Monzo card so I would recommend always selecting Savings.