I posted a general response to your question on this in the other forum posting you submitted.....but now you say the fresh tank was full going into Winter: I would start by checking the water line from fresh tank to the on/off fresh water valve in the wet bay leading to the water pump filter and water pump.
It is also possible with a very full fresh tank that the fresh water fill tube or vent line froze and split open.....which would leak some water from the tank.....and certainly any new water being added into the fresh fill port would also go onto the floor.
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