Phrag bud blasting

This phrag is a NOID, I'm afraid, but it's been an almost indestructible, faithfully blooming (sequentially) plant for three years. Until now.

Lately, every new bud, as it nears full development, doesn't open and just drops off. Where the bud joins with the bloom stalk, I've noticed a slight yellowing at that juncture. There's no noticeable rot, etc.

The plant appears healthy. Leaves are robust, roots are fine. No bugs anywhere. Its location on my southern windowsill is unchanged. What HAS changed is that it's now summer and the fresh air (well, fresh for NYC!) blows in.

The only changed variable is that constant breeze, but it doesn't seem logical that a spring/summer breeze could make a bud blast, does it? Other phals, etc. and dens in the same location are doing just fine.

Any clues, guys? I'm stuck here.

A question when was it re-potted last ? If the air is dry might have something to do with the blasting Gin

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Never put off until tomorrow what you can avoid all together.

It was repotted early this spring. The humidity varies here in NYC -- anywhere from 26% to 99% during spring and summer. This same situation has existed in previous years with this plant and there was never any bud blasting.