I think you can rule out bad film. Old film would not develop clear, it would be fogged. I suppose putting the film in the holder backwards is a possibility, but if you are experienced with 4x5 it is not likely. If the film is clear, as you say, that means it didn’t get any exposure or you ran it through the fixer first as has been mentioned. Unless your shutter is stuck, it has to be the latter.
I think mixing the chemicals the night before is a bad idea. If temperature control is the issue, you can very easily use a water bath to warm or cool (ice cubes) the solutions. Then they are not only fresh but you are less likely to mix them up.
About 25 years ago I returned from a photo outing with, I am sure, a bunch of prize winning images. Being excited, I rushed down to the darkroom to develop them and was surprised to see, as you did, clear film. I use developer one shot so that had gone down the drain but the fixer was still there and a quick check with my fingers confirmed my suspicions. My “fixer” was slimy. My working solution containers were and still are 32 oz. plastic Pepsi cups but in addition to being labeled “Developer”, Stop Bath”, “Fixer” and “Wash”, the developer cup has a bright red felt marker band around the top. It hasn’t happened again.
Jerome