It looks like you are using a DaskExecutor and the yellow Submitted states indicate that a task run has been submitted to Dask for execution.
1. Are the yellow tasks stuck and stay in Submitted state forever?
2. How did you define this polling mechanism - is it part of a mapped task? What is your max retries on that task?
Btw, not sure if this is helpful since you seem to have already implemented this, but
here is a Discourse topic that describes different ways of approaching similar use cases