My potted lilly pillies are losing their bottom leaves! Originally I became concerned because they were putting out flower buds but mostly dropping them instead of opening. There were a couple of little bald spots but now they've lost heaps of leaves pics in comments

I had them mulched but just took it off because the soil seemed to ALWAYS be moist (not super wet though, and due to seeming moist I wasn't watering very often), and I wondered if this could be contributing.

They were pretty root bound when I got them, I sliced through some of the outer roots as recommended in various places. Could this be a root issue? They get a little shade on the lower stems during the day but mostly full sun. Fairly windy position too, but I can't get around that where I live.

Located near Melbourne so hasn't been crazy hot or anything this summer.

Can anyone tell me what could possibly be going on/things I could try? I reeeeeally don't want to lose them!