this is a stumper.
If you are sure the tape is not catching (my thinking was that it was thick tape, but looking it up online it looks like a 5 mil thick tape, so likely not the issue. Does it conform to the wood of your sled? If so, the ridges on the wooden sled might be catching even with the tape, though this seems unlikely)
And you’ve said that the motors are running smoothly, so I am assuming that the chain is also moving on and off the sprockets smoothly (no chance it is popping off? This has been a problem for a lot of people, and it happens faster than the eye can see, usually manifesting as a crooked cut)
The angle and weight seem to be fine. It happens whether the router is engaged with the material, so it’s likely not the bit going through something dense.
I sanded mine too, I think it’s a good idea given the texture of the powder coating, but it shouldn’t take much sanding, and running a finger along it should let you feel if there is anything for the bearings to catch on
I have not applied anything to my bearings, and I don’t think you should have to. Do they spin freely?
This is likely a good idea as it will provide a nice flat surface. Here is a link to how I put mine on:
you’d have to use wood screws if your sled is wooden, but it should be the same process.
Please keep us updated. I really want to figure out what’s going on and help you fix it.