JP - I had the exact same experience. I contacted the manufacturer and was sent a second one, and it did the same thing. If it ain’t broke, don’t fix it.
You got a low end recoil assembly. Use a better product. A better product would use factory oem springs. BT Guide Rods makes the best aftermarket guide rod assemblies.I got one and installed it. I could not take down the pistol with this installed. The slide release would not disengage at all. I returned my stainless guide rod.
I had the same thing happen. I wrote to BT and they quickly sent me a second one and the same issue occurred. I sent both back and was refunded.
The weight difference is negligible from the polymer to steel guide rods so most don't even notice a change in recoil. The main reason people change them out is because it's believed that either polymer guide rods are crap or purely for the longevity but Glock has been running polymer guide rods forever and there's no issues with them. Same goes with Walther so unless you're paranoid, a perfectionist, OCD about steel or just want to spend more money on your gun, it's not worth it.
If your guide rod ever does fail, contact Walther and they'll either send you a new one for free under warranty or sell you one dirt cheap.