I think there were studies set up specifically to show no benefit of ivermectin. I think they were designed to fail purposefully. Take for example the one who selected only relatively young healthy individuals as participants. They would be the group expected to have the least amount of problems handling covid 19. And that is exactly what happened. The infection and complication rates were low in both the ivermectin and placebo side. The ivermectin still showed two days faster viral clearance but it was not statistically significant. So the "study" was able to say there was no benefit of taking ivermectin.

They specifically chose a group that likely would clear the virus on their own without any medication to show ivermectin would not help much. Of course it didn't because the group as a whole did not need medicinal assistance to get over the virus. Ivermectin still cleared the virus two days quicker, by their own end point determination, but not fast enough to be statistically significant.

So yes, I think there are trials set up specifically to show some drugs/treatments don't work, when the researchers don't want them to work. 

Another example is HCQ. It only has a chance to help anyone during the viral replication phase of covid 19. Yet the trials were all in a hospital setting. By the time a patient had deteriorated enough to be hospitalized the viral replication had already happened. So the hospital gave HCQ at a time it could not possibly do any good. So they "proved" it did not work by giving it at the wrong time.