Removing shaft problem

I’m trying to remove the shaft from a Simucube 2 Pro to install a Simcore shaft extender but after I removed the 4 bolts the shaft doesn’t get loose.

I wiggled it, used the tip (on Simcore website) of screwing a bolt an extra half turn once it bottoms out through the smaller screw holes, but I can’t make it come off.
Actually I never felt it bottomed out, but I feel a lot of resistance.
I even turned way more than 1 full turn after that big resistance point with no success.
I also tried to attach a wheel to have a better grip to wiggle it and pull, but it doesn’t come out.

Can I screw that bolt over and over until the hub gets loose? Or can it damage anything screwing the bolt too much?

Or is there any other tip to get the hub loose?