Hi, you could check if it's a solder issue if you monitors with e.g. an oscilloscope or a pattern analyzer the data output. However, at which Vdd/VddIO and ODR are you working? And after the setup did you follow the instruction of the app note p12?
You could also try to set the BDU bit and check what happens (CTRL_REG4 = 0x6F). It is recommended in this case:
If the reading of the acceleration data is particularly slow and cannot be synchronized (or it is not required) with either the XYZDA bit in the STATUS register or with the DRDY signal, it is strongly recommended to set the BDU (block data update) bit to 1 in the CTRL_REG4 register. This feature avoids the reading of values (most significant and least significant parts of the acceleration data) related to different samples. In particular, when the BDU is activated, the data registers related to each channel always contain the most recent acceleration data produced by the device, but, if the reading of a given pair (i.e. OUT_X_H and OUT_X_L, OUT_Y_H and OUT_Y_L, OUT_Z_H and OUT_Z_L) is initiated, the refresh for that pair is blocked until both MSB and LSB parts of the data are read.
Regards
