In singing, we are using parts of the body that are also used for swallowing, breathing, keeping food out of the lungs, and stabilizing the torso for strenuous tasks. No wonder that singing can sometimes be full of interfering tensions! Many of the myriad “tips” out there for singers are about trying to peel away these interferences so that the voice can operate more freely.
Tricky stuff. Sometimes technical problems have roots in strange places. Sometimes multiple issues magnify each other. Stay open and keep looking at what you’re doing from fresh angles. There is always something to learn. Or unlearn.