We have this feature in the upcoming GA release that prevents the deletion of EPHEMERAL_TEMP_VM

But as a workaround, you may either want to stop the CSE service where the OVA is installed. Powering off the OVA vm also brings down the service. Either of them is required to stop EPHEMERAL_TEMP_VM getting deleted. 

But, the above step should be done before the timeout happens. If you get to notice that it is looping on any existing phase. But timing this (stopping the service) requires little judgement on how fast the cluster creation happen.