Q.Ornamental Grasses
I planted new Little Kitten ornamental grasses last Sept with mulch base. They did well and went brown in the winter. I left them untouched through the winter as the blades were ornamental. I cut them down to about 3 in height in the spring. They are not showing any signs of sprouting yet this summer. Are they late bloomers or have they died?

You are in zone 5b and the growing zone for this grass is zones 5-8.
If you had any temperature below normal for your region; the grass may not have survived the winter.
Though ornamental grasses can be the last to make their appearances in the spring, with no new growth by now, I think you can say it is a loss for this year.
It may be worth checking if the greenhouse will warranty the plant; many reputable growers have a 1 year warranty on new perennials and shrubs.