I've had this issue since 2018!  Merch Services and QB Payment support never have an answer.  But I have noticed a few things over the years. When I run  ach on customer account that had in the last week or two had nsf's or fraud, I have to wait a few weeks to run again.  But when customer has funds in the account it is just a weird glitch that never gets fixed. So frustrating. And embarrasing when you have to call customer and say payment declined and no one can explain or fix.