IMU_FAST not logging

Enabled IMU_FAST as the only option under LOG_BITMASK in Full Parameter List hoping to get a faster logging rate than just “IMU” similar to ATT_FAST (see image 1). Didn’t enable any other "messages’ since I had no idea how much space/memory IMU_FAST would take. I DID try enabling it with other LOG_BITMASK options initially with the same result.

Using Ardcopter 4.1.1 Bi-directional on Matek H743 Mini with SD card logging.

No IMU data was logged at all (no IMU messages). See image 2.
Am I doing something wrong with regards to logging IMU_FAST or is this a “bug” or some other reason? Thanks!

log file 00000121.BIN (219.5 KB)