Unreliable Saves On Bulb/Astronomy

[jerryyyyyyyyyy]

Hi,
I am using a D800 added to my telescope and taking long exposures (600s). I have the folder and file naming set, but when I try to take a series of say 10-20 shots, one may appear in the folder, but then nothing.
It says "Capture" then goes to WAITING and runs for the whole 600s waiting again. Any ideas here?
JY
PS Have tried rebooting the camera etc.... I am using the dark current ROM flash.

2020-06-12 08_05_15-Observatory3.jpg (115.57 KiB) Viewed 2952 times

[jerryyyyyyyyyy]

My D800 had Long Exposure NR turned on by default. This takes a second dark exposure... Need to get that turned off routinely. Seems to come on as soon as camera is started.