I was called back to the site where I'd collected Colony 20 on Friday (3rd July 2020). I eventually made it there on Sunday. Life is busy.
There was still a small cluster of bees at the top of the tree. The most likely explanation is that the Queen is in that cluster. The bees rest of the swarm (in the hive) is busy making comb. No pollen is coming in.
The Queen is too high up for me to reach. If she's still alive today (7th July 2020) then it can't be for much longer.
I will have to do something with Colony 20 because they appear to be queenless.