How strange!
Firstly, I would suggest keeping a diary of times this happens, weather changes, farmers spraying their land, any different smells in the air, birds, foxes calling, wasing, drying machine on, if a behaviourist is needed it will be very helpful also exactly what she does, for how long etc. So start that as of today.

She should have settled into her new home by now, we are in June and if you moved some time last year it is plenty of time for her to have made it her territory.
You could try a DAP defuser to see if that helps at all..........
Just for an example, my girl began barking and growling at a certain time on an evening, just standing in the kitchen growling into the conservatory and growling at thin air to us, I could see nothing and checked all the logical reasons why she was doing this, I even began to think I may have a spirt

It went on night after night, and none of us could work it out.
Do you know what it was????? I have a large plant in my conservatory, which was casting a shadow on the floor, my girl could see it and was growling, I just stopped it by turning off one of my lights.

It can just be the most simple of things, that we don't notice. Perhaps the sun brings a scent to the house that is not noticed, it could be anything? Keep the diary and see if you can spot any similarities at all, then when you put it all together hopefully you will see a pattern.
It may be worth a vet check too, to check she is in no pain anywhere.