I have had a few people share with me that when they did the stick blender version of my mayo it did not work. I too had several failed batches after a ton of successful batches.
I set out to discover why! Well, I began to lift my blender too soon, before the mixture had a chance to emulsify.
You need to keep the stick blender on the bottom of the jar! Until about 1/3 to 1/2 of the mixture emulsifies. Then you can begin to lift it up and down a little to get all the oil mixed in.
Let me know if you try this and you have problems. I had to throw away $11.00 of good oil, so I know how frustrating it can be. I want you to succeed, so get back to me if you have problems, okay?