Is this a particularly long-running microflow, such as several minutes? I think I recall that the runtime checks for the microflow finishing quite frequently initially, but then the checking leaves a longer gap as the time the microflow is running increases. This can mean that for a very long-running microflow, it can be several seconds before it checks again after the microflow has actually finished. Hope I remembered that right. Someone please correct if this is wrong.
Experiencing the same issue in 7.7.1 -- maybe someone from Mendix (support) has a suggestion?