Clone request to DEMO/POV instances will not proceed and will give the following error message.
"The clone pre-flight check for valid capacity mapping has failed"
Unfortunately, this is an expected behavior.
We do not have an option to increase the size of a DEMO or POV instance as it is provisioned with the smallest DB capacity which is PICO. These instances also cannot grow automatically during a clone. So if the data coming in from the Source instance is bigger than what the target can accommodate, the clone will not proceed.
The clone might have worked in the past. It will work if the amount of data coming in from source could be accommodated in target.
The clone engine will try to analyse the capacity and give the error message if the target cannot be accommodated and show capacity error messages as it cannot auto-grow like SUB PROD instances.
If this instance was given by your account representatives, you can talk to them and advise getting a SUB PROD instance created so that you can schedule a clone to the new instance. This is an expected behavior for DEMO/POV instances.