This can happen sometimes, it is a safety mechanism.

It is very important that you FIRST loosen the nut on the adjuster bar by turning it Counter-Clockwise until it is about an inch above the main pole. Then you can turn the adjuster bar Clock-Wise to loosen the pole from the ceiling and lower the dome.

If you accidentally try to turn the adjuster bar before loosening the nut, it will tighten the pole in place. Once that happens it can be a challenge getting it un-done but not impossible. I personally like to use a good wrench or a pipe wrench to get it down when it’s stuck like that.

Here is an Un-Installation Video for the pole that will give you a visual of how to take it down =>