FIFO sampling of LSM6DSL and "missing" samples
I have programmed the LSM6DSL to a sample rate ODR of 26Hz, and set the FIFO ODR to 26Hz (I've also tried much higher FIFO ODR rates). I am only sampling the accelerometer. Every second, I read the FIFO and am expecting to find 26 samples. Or, at the very least, if I find 25 samples I expect to see 27 samples in the next second. I will read all of the samples out when depending on how many are in the FIFO.
However, what I am seeing is that I will have 26 samples, for say, 3-4 seconds, then 25 samples. Then back to 26 samples for 3-4 seconds, then 25 samples. It isn't always 3-4 seconds. Sometimes it's 2-3 seconds.
It appears I am losing data. I am not sampling at 26 Hz, but rather 25.*** Hz.
Is this expected behavior? How accurate is the clock?