Phal bud blast mystery

[Shadeflower]

as long as it's just a couple at the back that happens. I mean look at how many flowers it is trying to support.

Did most of them make it last year?

Most of the time it is a watering issue. Orchids need nutrients all the time so if you don't water regularly enough they can run out. In these times it is good to spray a little daily on to the air roots to provide more water and nutrients.
Lots just stop fertilizing in winter completely but you can see this phal is a winter bloomer. The rest of the year it will grow a leaf but it's main activity produing all these buds is this time of year. Now they do store nutrients all year long in the build up but they can easily run out and will just sacrifice a couple of back buds but if all the buds drop then than is a far more serious issue and there are several reasons that could contribute but if it's just the two at the back (and was last year too) then that is just the plant saying look I was bred to produce lots of flowers but with these temps this is the best I can do..

Last year as your only reference you say it flowered for one week only. That is of course far too short but can happen if the plant is still a bit immature. Like you say the plant has grown really well, there doesn't seem to be anything wong with it and I know the bud blast is like "oh no not again" but I am sure the flowers will last longer this time, unless there is an issue we can't see but I don't think it's time to panic just yet.