I ran into this same problem and finally had to either hands-on-glass myself or have teachers/students do the updates. I can't verify this for certain, but I believe it has something to do with the need to 'Agree to terms' that the 16.x update makes you click on glass. Again, I can't confirm this is the issue, but I am not able to remote update to 16.x either.

The other thing I ran into (and I really hope this isn't the case for you) is that once the iPadOS gets past a certain 'out of date' point, you have to use iTunes to update the device. I had two 6th gen iPads with older iOS's still on them. One had 11.x and another 13.x. I had to connect both to iTunes on my computer to run the update process. It worked just fine, but still is a pain in the rear.

I'm hoping someone knows the true answer, because I still have a number of devices that need 16.2 pushed to them.

Greg

The iPad is only seeing 15.7 update in Settings, so it's not even going as far as it could. Maybe that has something to do with it.

I wasn't really happy with the device update experience in Jamf School, just finding the exact serial number and which update it was listed in Jamf School as requesting makes no sense.

After updating to 15.7 on the device, I was able to push 16.2. 

We have 16.2, 16.11, 15.7 and 15.5. I tried to update to 16.3. The update status is 0 %. I waited over night but no success.

After six days still at 0 %.

Now the status has changed to failed. Last check-in 5 minutes ago.

It's been that way for over a year where it shows '0%' for both 'Downloading' and 'Installing'.

Though in saying that, I noticed the other day that it now finally shows an actual percentage instead of just 0%.

Was rather annoying over the last year, go to tell 200 iPads to update, they all show 'Downloading (0%)' for a good 30mins, then after a forced-refresh, they'll eventually update to 'Installing (0%)', then after about 10-15mins, they switch over to 'Failed (details)' where it says it can't determine the OS update status, besides already knowing the device is now up to date.