We have consulted with the manufacturer about the EOS mounts but could not find a decision to fix your problem.
We would like to offer you the following.
We have a number of EOS fitting samples that we think they are the best and we may send one of them to you. You'll change the fitting on one of the lens and see how it works. If it's Ok, you'll remove other fittings and mail them to us. And we'll ship you the 5 other samples.
These fittings are easy to change but we'll mail you an instruction how to do that.
If the problem is still on after changing the fitting you may return all 6 lenses back to us for a refund.