Re-rolling weekly challenges not working

Typically you get 4 chances to re-roll weekly challenges. With a new set of weekly challenges I decided to re-roll them, though 3 of the challenges did not re-roll and stayed the same. Now I have used the 4 limit of re-rolls, but 3 of the challenges stayed the same.

Can we get more re-rolls? I am not going to play the modes I have zero interest in, and it would be impossible to unlock the shotgun unless I do all of the weekly rewards. I think even if I did all of them I would still not be able to unlock it before the season ends unless the next week vastly increases the amount of tokens per challenge. Will the shotgun still be available for free once this season is over?