A recent article appearing online identified the risk of cancelling insurance.

https://thenewdaily.com.au/money/superannuation/2018/01/17/superannuation-change-insurance/

In the most simple terms if you are ill or even suspect you are ill do not cancel your insurance, until you have a diagnosis. If you do cancel your insurance then you may not receive your benefit. If you are replacing your cover then make sure the new cover is in place before cancelling the old cover