I brought mine in a poster tube on many airlines with no problem.
The one airline that gave me a problem was spirit. It was on the way back after Sukkos so it was empty (they didn't know that). The person scanning my boarding pass told me to go to the counter to pay. I went to the counter and told them that I wasn't paying $100 to bring this along and they can use it in good health. The two Spirit employee had a whole debate between each other and decided that there was no official rule for poster tubes. They came to the maskana that since I didn't pay for a carryon I'm not entitled to overhead space but I can keep it between my legs if I want (as if any flight attendant would let that fly/pun intended). I promptly walked onto the airplane and put it in the overhead bin.
So definitely a YMMV
