I know of no evidence or reason why the pistil of a daylily would "close" after being pollinated. As far as I know that is not something that is typical in plants. In many plants researchers pollinate the flower with one pollen and then pollinate it later with a second different pollen. The first pollen can have an advantage but the second pollen does not necessarily fail completely.
When a diploid is crossed with a tetraploid or a tetraploid is crossed with a diploid there are several different possibilities that can happen.
1) the flower does not form a pod and drops off more or less as expected.
2) the flower forms a pod
2a) the pod falls off after 7 to 10 days usually
2b) the pod stays and seems to develop for several weeks and then falls off
2c) the pod stays on and matures with no seeds
2d) the pod stays on and matures and has one or more seemingly normal looking seeds
3a) the seeds do not germinate
3b) one or more of the seeds germinates to produce a seedling.
If insects did not also pollinate the flower with pollen of the correct ploidy then if a seedling is produced it is most likely a triploid.
If the pod produces more or less a normal number of seeds and they germinate reasonably well to produce a relatively normal number of seedlings then the flower was most likely pollinated by an insect with pollen of the correct ploidy and the seedlings have the same ploidy as the pod parent.
If only one, or rarely two or three seedlings are produced then they may be triploids. However, if the pod parent is known to produce few seeds when pollinated with pollen of the correct ploidy all bets are off - the seedlings might be triploids or they might have the same ploidy as the pollen parent and have been produced by an insect pollination.
If the pod produces many good mature seeds and most of the seeds tested germinate then the seedlings are almost certainly the same ploidy as the pod parent and an insect was involved in pollinating the flower. Cross-ploidy pollinations that worked may produce one or rarely two good seeds in a pod.
Of 1607 pollinations between diploids and tetraploids and vice versa Arisumi managed 155 firm mature looking seeds. From 100 of those seeds only 23 germinated and only 17 seedlings survived the young seedling stage. For most of the crosses Arisumi made 6 pollinations. From 16 crosses each with 6 pollinations Arisumi only had one seedling each. He managed 2 seedlings from 4 crosses that had 6 to 10 pollinations each. He managed 3 seedlings from a cross with 10 pollinations.
All the seedlings that survived were triploids.
