synchronization between imu measurement and stereo images

[SinnedHog]

I performed an imu-camera calibration using the open source library Kalibr (https://github.com/ethz-asl/kalibr) to find out the delay between the imu measurements and stereo images. I fixed the camera exposure time to 1ms and the result from the calibration indicated that the camera is 10ms slower than the imu timestamp. I have read in one of the github post (https://github.com/luxonis/depthai-core/issues/516) that even though the imu and stereo cameras are not hardware sync but they are running on the same clock. Therefore, the delay should not be larger than half of the camera exposure time, which in this case is 0.5ms. Is the result from kalibr expected? My experience from using kalibr is that it has been reliably given me accurate estimate. Has anyone encountered the same issue before?