There is certainly something odd about this camera when using longer duration. I tested with a pristine installations.

If you capture with a 1.0 sec exposure, the image downloads almost instantly.

If you capture with a 10.0 sec exposure, it takes about 11.5 seconds to download the image after exposure stops.
If you capture with a 15.0 sec exposure, the image downloads almost instantly.
If you capture with a 18.0 sec exposure, the image downloads almost instantly.
If you capture with a 20.0 sec exposure, the image never downloads and EKOS will just hang waiting for the data. Have to kill indiserver and the indi_qhy_ccd driver, as well as unplug and re-plug the polemaster to resume capture.
21.0 sec exposure is fine.
29.0 sec is fine.
30.0 sec bombs just like 20.0 sec did.
40.0 sec bombs just like 20.0 sec did.
50.1 sec took 52 seconds to download after exposure ended.
89.0 sec took 91 sec to download image.
93.0 sec worked fine.
118.0 sec worked fine.

It appears that multiples of 10.0 seconds will cause issues with the driver and/or camera. Getting close to a multiple of 10.0 sec can sometimes trigger a situation where it appears that a second image is captured and sent since the delay in downloading appears to be equal to the exposure time.

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