skewer for a Yakima roof rack?

In my divorce I lost the hitch mount Yakima roof rack my husband and I had...but gained the Yakima fork-mount roof rack. I installed it myself (proudly) but find it a little quirky to use. My road bike seems to do just fine on it, but my mountain bike with disc brakes makes it hard to clamp properly...in fact, I had it up there and the thing popped open and my bike fell...good thing I was going slowly and it fell on to the roof of the car. I would rather have a scratched car than a scratched bike! The disc brake does not APPEAR to be interfering with the skewer clamping mechanism, it seems difficult on BOTH bikes to get the skewers to tighten properly...a lot of wiggling and adjusting goes in to it. I am thinking of replacing the skewers? It HAS successfully held both bikes, so I know it can, it is just a pain in the neck. Any words of advice?

Call Yakima. I have had excellent customer service from them.

Yes, call Yakima. You may find that you need two different mounts as the mtb fork may need a specific mount. Be sure to tell them what kind of fork you have and if it has a thru-axle, etc.

Why didn't I think of that? Probably because every time I think of calling a company, I think of all the times when I call about my cable, my computer, or something of the like and get someone in India reading off a script.
I will give Yakima a call and see what they think!