Rejection of UK visa got an entire delegation coming for University-sponsored one-week training [closed]

Recently, UK visit visa of entire delegation comprising of 15 full time faculty members of our university based in Pakistan and ranked top most in private sector universities has been rejected.

The reasons for refusal are astonishing. Almost all of us had different reasons for refusal through we provided same documents and were going for a one week academic training.

One reason is that the refusal letter states we had not provided any proof that we will be back after the training is over though we had attached travel reservations and the facilitation letter offered by university also clearly mentioning the dates of the start and end of training.

Is there any other document required to provide an evidence that the i will be back on very next day the training is over?

Secondly, the refusal letter states that i have not mentioned what i will do other than the 20 hours of tuition in the training session. How do i provide an evidence that my sole purpose is attending the training session and i have no other business there?

We are left with 15 days now for the training to start. Could you highlight the issues in our applications? will it prove good to re apply at this point of time?