Since things have cooled down here's what I know regarding Hagrid. This could still be wrong but I'm confident enough to run it.
Hagrid began testing in March 2019. In May 2019 it was discovered the axils of the trains were wearing down faster than expected, causing one vehicle to partially derail. Intamin and UC worked around the clock to solve the issue. Due to that discovery at the last minute the attraction stopped its scheduled testing and focused on fixing the issue. Vehicles were repaired, testing resumed, but the vehicles were slow to become certified as the repairs were made (vehicles are required to run a certain amount of time). As such they couldn't do the testing required to reach the 10 or 12 trains on the track before opening. So when the ride opened not all the ride vehicles were ready AND the ride controls were not tested for more. This is also why there is a camera positioned at the end of the ride filming the train wheel assemblies.
There were also two other issues they were facing at the time: one that was quickly solved and the worries about loading the vehicles. UOR slowed down the belts to allow for a longer boarding time which slowed down dispatches, causing more capacity issues. As we've seen over the past few weeks the belts have been sped up and this is no longer an issue.
What this boils down to is a ride that saw several major issues at the last minute that could be overcome but caused a delay in testing at their desired capacity. "Well why didn't they run softs?" they literally couldn't. "Why didn't they change the opening date?" corporate mandated the opening date and pushed for an early announcement. It was a combination of many bad breaks and last minute issues that lead us to where we are today: performing the testing that should have occurred in May happening in August to get the ride up to capacity.