active token got stuck in user task

I start a process and submit a user task 1 . there is an active token on user task 2 in runtime and when we change process mode in history the active token disappear; also in cockpit in user task section we cant see user task 2 .
this process in my application run several times in large scale , and this problem occurs at some process, not on all process.

can you share bpmn file


hi, the active token has stocked in user task 2

Do you take into consideration the multi instance situation for user task 2 here? It would be better to see the bpmn file

I check all multi instance task situation such as completion condition, collection,…