Save my phal: Clear soft spots on new leaves?

[theloyalplum]

Hi Everyone! Tis be a day or sadness.

I need help IDing and finding a solution a problem that's been bugging me for a few weeks now. My phal bellina's new leaves are showing clear, watery spots (that start as small white specks) that spread and spread. Pictured here:


I've tried cutting away a good amount into healthy tissue (sterilization's a given), also Physan 20 in case it was fungal (perhaps it still is?).

I'm worried. Another one of my phals has shown the same problem. I've quarantined them in the meantime. Any help is very welcome.