To find the interval for the disabled HDR setting, try looking at the Meta Data timestamp of the images to at least get a boundary of when it happened (time between the last image with HDR enabled and the first images with it Disabled).

I am getting this same HDR is on Error Message in the latest Firmware Update with an Unleashed '18. Firmware A 2.2.4 B 2.2.1 C 2.2.0. I am also seeing multiple other failures, like in Timelapse it only will take the initial image. It will count all other intervals as having been completed, but only ...