Dear @Xiang.Li,
Are you post-processing the linearization output from FAST v7 using the old GetMats.m script from MBC: matlab-toolbox/GetMats.m at main · OpenFAST/matlab-toolbox · GitHub (rather than, say, the new fx_getMats.m script for OpenFAST: matlab-toolbox/fx_getMats.m at main · OpenFAST/matlab-toolbox · GitHub)? In the old GetMats.m script, the order of the states (rows in the B matrix) is read in as variable DescStates into MATLAB and the order of control inputs (columns in the B matrix) is given as variable DescCntrlInpt.
After azimuth averaging, the influence of the generator-azimuth state should be eliminated, which should then be removed from the linear model before use. This is discussed e.g. in the following forum topic: FAST linearization V7.
Best regards,