Yes, it's the full sun that bleaches out the leaves. And yes, you get lots of blooms because it gets so much sun. I choose to grow mine in less sun so the foliage looks pristine, but I'm sure I don't get nearly as many flowers as I would if I grew in full sun. I do get flowers, mind you, just not loads of them all at once.

My Hoya lacunosa grows in a north window and blooms almost all the time - at least a few at a time. But my mother's grows in an east window and blooms consistently, too, with more flower spurs blooming at once. It's a trade off...

Denise in Omaha

Different plants are adapted to grow with different light intensities in nature and if you go too far outside those limits in cultivation they will either not bloom or they will show stress. Plants have a few options if they receive too much light and those are to turn red in an attempt to protect the chlorophyll containing cells, much like we get a tan to protect our cells from the damage of UV radiation. The other option is for the plant to remove the chlorophyll from the leaves and store it in other more protected areas like the stem. This happens in temperate areas of the world each year come fall and this is why the leaves of trees become red and yellow. The red and yellow pigments are always there but they are usually masked by the green chlorophyll when it is present.

Many plants in cultivation bloom the best when they are slightly stressed but I believe that it is better to grow a plant so that it still looks good and blooms vs. blooms well but looks overly stressed. You might want to try moving the plant back from the window just a little in hopes of lessening the amount of direct light exposure or maybe using a sheer curtain to protect the plant a little more. There is a trick to greening a plant back up and that is to use 1 tbsp of epsom salts per gallon of water. Epsom salts is Magnesium sulfate which is a critical component in the production of chlorophyll.

Good luck with your plant.

Mike