How disappointing for you Waddy - strange for them to have settled for a couple of weeks & then go
I've already started feeding mine - they only took down about half of their "settling in syrup" & have been rapidly expanding in their numbers over the past few weeks. I wasn't too sure of how much stores they had when we got the sudden downpours last week, so I popped-in a litre of syrup just in case. Checked yesterday morning & they'd taken the lot

So they had another 1:2 syrup in between showers.
Hopefully the weather will improve some - or they'll be going through a kilo of sugar a week at the rate