Water parameter's described as good/normal,within range,are subjective opinion's.
Need number's.
Meds can sometimes have undesireable affect on fishes and also plant's.
According to previous post's,you treated for fungus in Feb and now with API general cure for ??
My money is still on diatom's that normally go away as mentioned afte a couple month's but have been known to hang around longer.
Can wipe the diatom's off the glass with clean paper towel ,rub the stuff off large leaves,vaccum around the plant's to remove it from the substrate,and keep filter material cleaned regularly.
Otocinclus love diatom algae, but your previous post's indicate molllie's in the tank which thrive in hard alkaline water that otocinclus don't appreciate .