Q.growing beefsteak tomatoes in grow bags
I am trying to grow beefsteak tomatoes in grow bags. The plants are growing ok but the flowers are not setting. What have I done wrong?

There could be a few reasons.
Cool evening, extreme daytime heat, shallow watering, lack of pollination, and a few others.
I have listed a few links that can help you pinpoint the problem.
https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-upside-down.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/pollinate-tomatoes.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-blossoms-no-tomatoes.htm