Second time having this issue
When using Mystic frontier, I was able to select my team of familiars, select the adventure and then start the adventure.
You then need to select your "tasks" during each stage so that you can roll to receive rewards/pouches but after receiving the error "busy, try again" or whatever it says- I can no longer select a task after that. Every task that you click on during that stage opens but you can't select any of them for the pouches/rewards. They are all clickable but clicking on a task doesn't do anything. No matter how many times you click, hit enter, interact key or anything it doesn't allow you to select your task/mission. The only thing you can do is click skip to the end at stage 5. Each phase after you encounter the bug does not allow you to select a "task" for you to roll for rewards. I received it both times after the first task and at the beginning of stage 2 so that stage and subsequent tasks/stages are all lost as you have to skip them.
Not sure if anyone else has received this same bug but it's the second time now.