mmmmm, juicy....

[Mr.Fakename]

Can't say about mannii flava, but alba/flava of other Phal species have been notorious for being either slow growing, easily sulking, or very hard to breed with.
Javanica alba comes to mind.

Some plants don't accept pollination at all. I've tried maybe 15 flowers over 2 years on my Angraecum Veitchii, that bastard always drops the flowers.

And sometimes even non viable pollinia will seemingly work, until you crack the pod open and see dud seeds without embryos.