Happens. All. The. Time. Usually due to issues beyond your control. Misting too harshly (I use a very fine spray when I mist, using one of those small pump misters) can induce damage on embryonic leaves.

Would not hurt to check for pests (but if you are treating regularly, this should not be an issue).

I checked for pests and didn't see anything but I'm concerned about broad mites. Forbid treats spider mites but not broad mites. These little _ _ _kers are the worst! I can't find anything that will obliterate them once and for all,

Too wet of a mix for too long will cause thicker leaved hoyas to abort their new leaves. ..less oxygen for the roots...also I have your hoyas ready Monica.The hairy one is putting out new leaves!

Thanks for the info Jimmy. I guess I've been misting too much (which I was doing to keep any pests off the leaves!) Go figure!

I also wanted to tell you that Environmental Science division of Bayer just launched a new product May 1st called Altus. Nurseries and greenhouse growers are buzzing about it. It kills all plant sucking insects. It's been in development for about 8 years and the last 3 years were to refine the active ingredient for ornamental growing. It's also safe for citrus trees and most vegetables, I believe. Oh, and it can be used as a foliar spray or drench.

I'm trying to get my hands on some and will certainly share with you :-)

Losing new growth is the story of my life :P But it is only some varieties that do it for me. (Multiflora, everytime!)