Never had an issue with that myself. Since the mission is set for straight lines, curve size values are ignored. Unless there is a glitch in the software some place. Haven't seen that effect anything before. The OP stated the mismatch error, but I don't see where an upload failure would be.
Seeing more detailed info on the error, I do agree that probably is not the related to the error message.
But his mission that works they are all set for zero. The mission that fails they are not all set to zero, and nether is the default.
In the past having the default setting to curved turns set to zero, if adding waypoints they would stay at zero.
If you inserted a waypoint between two all ready existing waypoints the new waypont would not be at zero.
In the past this was in a thread and I have seen it many times, I tried reproduce it just now, but of coarse it works like you think it should. It may something to do with the cache from the browser.
Example of the cache, load up his failed mission, look at his default curve size, change to anything different, add a couple of waypoints. Close the mission hub, reload his mission. The added waypoints will be gone (of coarse). Then look at the default curve size, it will be what every you changed it to.
Anyways, back to the OP problem.
Rod