If you have it hooked up to city/shore water source, there is no need to run the onboard pump (interior switch) as it can cause problems with check valve in the pump resulting in your exact problem.
Do a search for reset of pump check valve or fresh tank filling. There are hundreds of posts about the problem and how to reset the check valve.
And it is possible that if you have the multifunction water valve panel type, they are not set correctly, but you should be be able to match the valve setting pictures with the desired function.
Scott and Liz - Southern NM
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