I have an Onc. Sharry baby that hasn't bloomed in over a year. It has 3 new growths that have matured since they started growing in November 2012. Now new growths are starting and I repotted it into a larger pot from sphagnum to bark mix. It is under T5s, tips of leaves are about 5 inches from the tubes. I've had a little trouble with drying leaf tips. I thought it may not be cool enough at night but my phals, paphs, catts, ect. are blooming just fine, even some of the parvi paphs that are supposed to like really cool temps are spiking.
Another thing I noticed is that the p-bulbs got to full size, even bigger than those on previous growths, but the leaves aren't as long and are stiff and stick out, they aren't long enough to droop a little.
I haven't had mine for more than about 6 months. But I just saw a spike today. I am growing it with a lot less light. I wouldn't think the extra light yours is getting would prevent blooming, but maybe....Mine does get a cooler night by about 10 degrees. Approx. 65 and 55 in the winter in the greenhouse. Not much else I can offer as tips since mine is fairly new to me.
Hmm...
Upright foliage is good, so it would seem it's getting enough light ...
I'm not aware of this needing a cool period to bloom - mine grows outside, so it gets VERY cool, but I have never heard of that being a requirement for blooming ...
Onc. including Sharry Baby can have Calcium deficientcy whic impacts spiking. I found that when I added MagiCal to my regime, about 3 months later, all my Oncidiums spiked!
(I use about 1/2 teaspoon MagiCal /gal of water about every 2-3 weeks. I got the MagiCal from Amazon. I was abouat $10 for a 1.5 liter bottle which should last a LONG time)
Indeed they like light. But too much light can inhibit blooming. Also calcium is a requirement for oncids to bloom well. If the leaves are short but the pbulbs large, it could be too much light. Sharry Baby likes a medium light somewhere between catts and phals. Mine bloomed fine with my phal light.