If you are using bamboo elainjoyce, your yarn may not be playing nicely with the needles and your tip is probably not lace which leads to your yarn not gliding easily and having difficulty sliding the tip into the back loop of the knit stitch. . I have discovered through trial and error, it's best to use lace tip needles for any type of KFB, k2tog, etc. So much easier to do those stitches. Give it a try with a lace needle. You'll discover a world of difference.
I have noticed the same thing. Lace work for me is not good with bamboo.
Hope your solution works for you.