I have a Kalotermes flavicollis royal pair since their flights in October of 2020. They laid eggs but those didn't develop for well over many months. Only mid-summer of this year they got their first 4 workers and another bigger batch of eggs. Their development seems to be quite long in my experience. You may have to change up their food, I had to switch from tissue paper to some other toilet paper, which is more rich in cellulose.
I have been an 'ant-husiast' for over 4.5 years.
I have kept over 80 species of ants so far.
Most of the species I keep has been collected by me during travel.
I am an amateur researcher and identifier, working my way to professional Myrmecology.
Glad to help others when needed